Chinese Physics C

Highlights

Physical parameter regression from black hole images using a multiscale adaptive neural network
Jialei Wei, Ao Liu, Dejiang Li, Cuihong Wen

2025, 49(12): 125105. doi: 10.1088/1674-1137/adf542

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High-precision regression of physical parameters from black hole images generated by General Relativistic Ray Tracing (GRRT) is essential for investigating spacetime curvature and advancing black hole astrophysics. However, owing to limitations in observational resolution, high observational costs, and imbalanced distributions of positive and negative samples, black hole images often suffer from data scarcity, sparse parameter spaces, and complex structural characteristics. These factors pose significant challenges to conventional regression methods based on simplified physical models. To overcome these challenges, this study introduces the Multiscale Adaptive Network (MANet), a novel regression framework grounded in deep learning. MANet integrates an Adaptive Channel Attention (ACA) module to selectively enhance features in physically informative regions. Meanwhile, a Multiscale Enhancement Feature Pyramid (MEFP) is employed to capture fine-grained spatial structures, such as photon rings and accretion disks, while alleviating information loss due to downsampling. Experimental evaluations on GRRT-simulated datasets demonstrate that MANet substantially improves parameter estimation accuracy and generalization capability in high-dimensional parameter spaces, outperforming existing baseline approaches. This framework presents a promising avenue for high-precision parameter regression in Event Horizon Telescope (EHT) data analysis and broader astrophysical imaging applications characterized by sparse and noisy data.
On the pole trajectory of the subthreshold negative parity nucleon with varying pion masses
Qu-Zhi Li, Zhiguang Xiao, Han-Qing Zheng

2025, 49(12): 123103. doi: 10.1088/1674-1137/adfa02

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We study the pole trajectory of the recently established subthreshold negative-parity nucleon pole, namely the $N^*(920)$, with varying pion masses in the scheme of linear σ model with nucleons, using the $N/D$ unitarization method. We find that, as the pion mass increases, the pole moves toward the real axis. For larger pion masses, at tree level, the pole falls to a specific point on u-channel cut and crosses to the adjacent Riemann sheet defined by the logarithmic u-channel cut. At the one-loop level, the pole does not meet the u-cut up to $m_\pi=0.36$ GeV. We also re-examined the σ pole trajectory and found it to be in good agreement with the Roy equation analysis result.
Feasibility study of measuring interaction cross sections of hypernuclei produced in projectile fragmentation reactions with WASA-FRS setup
Yiming Gao, Yoshiki K. Tanaka, Vasyl Drozd, Hiroyuki Ekawa, Samuel Escrig, Yan He, Ayumi Kasagi, Enqiang Liu, Manami Nakagawa, Christophe Rappold, Takehiko R. Saito, Ryohei Sekiya, He Wang, Ayari Yanai, Xiaohong Zhou

2025, 49(12): 124003. doi: 10.1088/1674-1137/adf4b2

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A novel method is proposed to measure the interaction cross sections of short-lived hypernuclei with the WASA-FRS experimental setup at GSI and FAIR. The interaction cross sections of hypernuclei, produced in projectile fragmentation reactions at relativistic energies, can be determined from their production point distribution within a target. The feasibility of such a measurement is evaluated through detailed Monte Carlo simulations. The results indicate that an aimed uncertainty on the order of 10% can be achieved for the case of a hypertriton, demonstrating the potential of this method for studying matter radii and the possible hyperon halo structure of hypernuclei.

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Spatially covariant gravity with two degrees of freedom in the presence of an auxiliary scalar field: Hamiltonian analysis
Jun-Cheng Zhu, Shu-Yu Li, Xian Gao

Published: 2025-12-22

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Published: 2025-12-22

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Off-shell modifications of the pion generalized parton distributions and transverse momentum dependent parton distributions
Jin-Li Zhang

Published: 2025-12-18, doi: 10.1088/1674-1137/ae28ea

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Published: 2025-12-18, doi: 10.1088/1674-1137/ae28ea

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A Classical Interpretation of the Nonrelativistic Quark Potential Model: Color Charge Definition and the Meson Mass-Radius Relationship
ZhiGuang Tan, YouNeng Guo, ShengJie Wang, Hua Zheng

Published: 2025-12-16, doi: 10.1088/1674-1137/ae28e9

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Published: 2025-12-16, doi: 10.1088/1674-1137/ae28e9

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95 GeV Higgs boson and nano-Hertz gravitational waves from domain walls in the next-to-two-Higgs-doublet model
Haotian Xu, Yufei Wang, Xiao-Fang Han, Lei Wang

2026, 50(1): 013108-013108-14. doi: 10.1088/1674-1137/ae2082

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This study explores the diphoton and $b\bar{b}$ excesses at 95.4 GeV, as well as nano-Hertz gravitational waves originating from domain walls, within the framework of the next-to-two-Higgs-doublet model (N2HDM), which extends the two-Higgs-doublet model by introducing a real singlet scalar subject to a discrete $Z_2$ symmetry. The $Z_2$ symmetry is spontaneously broken by the non-zero vacuum expectation value of the singlet scalar, $v_s$, which leads to the formation of domain walls. Two different scenarios are discussed: in scenario A, the 95.4 GeV Higgs boson predominantly originates from the singlet field, while in scenario B, it arises mainly from the CP-even components of the Higgs doublets. Accounting for relevant theoretical and experimental constraints, scenario A can fully account for both the diphoton and $b\bar{b}$ excesses at 95.4 GeV within the $1\sigma$ range. In the parameter space accommodating both excesses, scenario A fails to provide a valid explanation for the NANOGrav data up to $v_s=$ 1000 TeV, and the predicted gravitational wave spectrum can exceed the SKA sensitivity curve in the low frequency region. Scenario B only marginally accounts for the diphoton and $b\bar{b}$ excesses at the $1\sigma$ level, but can simultaneously explain the NANOGrav data well.

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Alpha-decay systematics and a new scaling law in heavy and superheavy nuclei
Hisham Anwer, A. R. Abdulghany

2026, 50(1): 014111-014111-16. doi: 10.1088/1674-1137/ae0307

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This paper presents a systematic investigation of α-decay properties in even-even isotopic chains of Po ($ Z=84 $), Cm ($ Z=96 $), Hs ($ Z=108 $), and Fl ($ Z=114 $) using a semi-classical approach. Ground-state properties, including binding energies and nucleon density distributions, are calculated by minimizing a Skyrme-based energy density functional augmented with microscopic corrections. The derived nuclear densities and $ Q_\alpha $-values are used to construct the α decay potential through the double-folding model (DFM). The α-decay dynamics are treated quantum mechanically based on the preformed cluster model (PCM) within the Wentzel-Kramers-Brillouin (WKB) approximation. The analysis reveals distinct signatures of spherical shell closures at $ N=126 $ and $ N=184 $, along with secondary anomalies near $ N = 148 $, $ 152 $, and $ 162 $, which are consistent with deformed sub-shell effects predicted by nuclear structure models. The signature of daughter nuclear stability is systematically observed through one or more of the following features: shortened α-decay half-lives, enhanced $ Q_\alpha $ values, increased penetrabilities, and/or reduced assault frequencies. A new universal scaling relation, relating the decay half-lives and a scaled combination of nuclear charge and decay energy, is established, showing strong correlation across a wide mass range. Systematic comparisons demonstrate particular predictive advantages for superheavy nuclei, with the proposed method accurately reproducing observed half-life variations across all isotopic chains. The results confirm the sensitivity of α-decay observables to both spherical and deformed shell effects and reinforce the role of α-decay systematics as powerful tools for probing nuclear structure and guiding predictions in unexplored regions of the nuclear chart.

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Investigation of resonances in the Σ(1/2^–) system based on the chiral quark model
Yu Yao, Xuejie Liu, Xiaoyun Chen, Yuheng Wu, Jialun Ping, Yue Tan, Qi Huang

2026, 50(2): 023109-023109-11. doi: 10.1088/1674-1137/ae18af

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In this work, we investigate the resonance structures in the $ \Sigma(1/2^-) $ system from both three-quark and five-quark perspectives within the framework of the chiral quark model. An accurate few-body computational approach, the Gaussian expansion method, is employed to construct the orbital wave functions of multiquark states. To reduce the model dependence on parameters, we fit two sets of parameters to check the stability of the results. The calculations show that our results remain stable despite changes in the parameters. In the three-quark calculations, two $ \Sigma(1/2^-) $ states are obtained with energies around 1.8 GeV, which are good candidates for the experimentally observed $ \Sigma(1750) $ and $ \Sigma(1900) $. In the five-quark configuration, several stable resonance states are identified, including $ \Sigma \pi $, $ N \bar{K} $, and $ N \bar{K}^{*} $. These resonance states survive the channel-coupling calculations under the complex-scaling framework and manifest as stable structures. Our results support the existence of a two-pole structure for the $ \Sigma(1/2^-) $ system, predominantly composed of $ \Sigma \pi $ and $ N \bar{K} $ configurations, analogous to the well-known $ \Lambda(1380) $-$ \Lambda(1405) $ ($ \Sigma \pi $-$ N \bar{K} $) system. On the other hand, although the energy of the $ N \bar{K}^{*} $ configuration is close to that of $ \Sigma(1750) $ and $ \Sigma(1900) $, the obtained width is not consistent with the experimental values. This suggests that the $ N \bar{K}^{*} $ state needs to mix with three-quark components to better explain the experimental $ \Sigma(1750) $ and $ \Sigma(1900) $ states. According to our decay width calculations, the predicted two resonance states are primarily composed of $ \Sigma \pi $ and $ N \bar{K} $, with their main decay channel being $ \Lambda \pi $. Therefore, we encourage experimental groups to search for the predicted two-pole structure of the $ \Sigma(1/2^-) $ system in the invariant mass spectrum of $ \Lambda \pi $.

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Current Issued

2025 Vol. 49, No. 12
Published: 02 December 2025

Particles And Fields
Nuclear Physics
Particle And Nuclear Astrophysics And Cosmology