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.

China

Jialei Wei

Ao Liu

Dejiang Li

Cuihong Wen

Physical parameter regression from black hole images using a multiscale adaptive neural network * Supported by the Natural Science Foundation of Hunan Province under grant No. 2023JJ30384; the National Natural Science Foundation of China under Grants No. 12374408; the University Students' Innovation and Entrepreneurship Training Program Project

We perform the first computation of phase-transition parameters to cubic order in $ \lambda\sim m^2/T^2 $ , where $\textit{m}$ is the scalar mass and $\textit{T}$ is the temperature, in a simple model resembling the Higgs sector of the SMEFT. We use dimensional reduction, including 1-loop matching corrections for terms of dimension 6 (in 4-dimensional units), 2-loop contributions for dimension-4 ones and 3-loops for the squared mass. We precisely quantify the size of the different corrections, including renormalization-group running as well as quantum effects from light fields in the effective theory provided by the Coleman-Weinberg potential, and discuss briefly the implications for gravitational waves. Our results suggest that, for strong phase transitions, 1-loop corrections from dimension-6 operators can compete with 2-loop ones from quartic couplings and largely surpass those from 3-loop thermal masses.

Spain

Mikael Chala

Luis Gil

Zhe Ren

Phase transitions in dimensional reduction up to three loops * Supported by MCIN/AEI (10.13039/501100011033) and ERDF (grants PID2021-128396NB-I00 and PID2022-139466NB-C22), from the Junta de Andalucía grants FQM 101 and P21-00199 and from Consejería de Universidad, Investigación e Innovación, Gobierno de España and Unión Europea – NextGenerationEU under grants AST22 6.5 and CNS2022-136024. MC and LG are further supported by the RyC and FPU programs under contract numbers RYC2019-027155-I and FPU23/02026, respectively.

This paper presents a systematic study of hyperon non-leptonic two-body decays induced by light quark transitions, particularly the $ s \rightarrow u\bar{u}d $ process, within the framework of $\textit{SU}$(3) flavor symmetry. The effective weak Hamiltonian is decomposed into irreducible $\textit{SU}$(3) representations, including the 27-plet and octet components, and applied to analyze decays of octet and decuplet baryons and charmed baryons. Both the irreducible representation amplitude (IRA) approach and the topological diagrammatic analysis (TDA) are employed to construct decay amplitudes and constrain the parameter space. $\textit{SU}$(3) symmetry-breaking effects arising from the strange quark mass are incorporated systematically. A global fit to current experimental data allows us to extract form factors and predict branching ratios and asymmetry parameters for several decay channels. Our results demonstrate the predictive power of $\textit{SU}$(3) flavor symmetry while highlighting significant symmetry-breaking effects, especially in amplitudes related to the 27-plet. Notably, the $ \Sigma^+ \rightarrow p\pi^0 $ decay channel exhibits a deviation exceeding $ 1\sigma $ from experimental measurements, suggesting the possible presence of new decay mechanisms or contributions beyond the Standard Model. Besides, we also evaluate the size of symmetry breaking. However, the large uncertainty of the experimental data makes it difficult to precisely determine the value of symmetry breaking. We strongly recommend that future experimental efforts aim to reduce the measurement uncertainties, especially for the processes $ \Lambda^0\to p\pi^- $ and $ \Lambda^0\to n\pi^0 $ , which have larger experimental errors compared to other data and play an important role in determining the symmetry breaking parameter. This study provides a systematic framework for future tests of the Standard Model and the search for new physics in hyperon decays.

Xin Wu

Qi Chen

Ye Xing

Zhi-Peng Xing

Ruilin Zhu

$\textit{SU}$(3) flavor symmetry analysis of hyperon non-leptonic two body decays * Ruilin Zhu is supported by NSFC (12322503, 12075124) and the Natural Science Foundation of Jiangsu (BK20211267). Zhi-Peng Xing is supported by NSFC (12375088, 12335003, 12405113). Ye Xing is supported by NSFC (12005294)

We present an investigation on cosmological implications resulting from spontaneous dark $ S U(2)_d $ symmetry breaking in conjunction with the Witten effect. Furthermore, we examine the mass of hidden monopoles generated by phase transition as well as the impact of axion-monopole interactions on the axion mass. Following spontaneous breaking of the PQ symmetry, axions emitted by cosmic strings or domain walls as well as hidden monopoles generated during this transition may collectively contribute to the observed dark matter relic density. Additionally, the stochastic gravitational wave background generated by sub-GeV phase transitions and by the decay of axionic domain walls formed during sub-ZeV phase transitions could account for the low-frequency gravitational wave signals detected by PTA experiments.

Ruiyu Zhou

Ligong Bian

Gravitational waves and dark matter with Witten effect * Supported by the National Key Research and Development Program of China (2021YFC2203004). Ruiyu Zhou is supported by the National Natural Science Foundation of China (12305109, 12147102), Chongqing Natural Science Foundation project (CSTB2022NSCQ-MSX0534), and Science and Technology Research Project of Chongqing Municipal Education Commission (KJQN202300614). Ligong Bian is supported by the National Natural Science Foundation of China (12322505, 12347101). Ligong Bian also acknowledges Chongqing Natural Science Foundation (CSTB2024NSCQ-JQX0022) and Chongqing Talents: Exceptional Young Talents Project (cstc2024ycjhbgzxm0020).

We introduce a novel level crossing phenomenon in the mass mixing between QCD axions: one canonical QCD axion and one $ Z_{{\cal{N}}} $ axion. The level crossing can occur at or slightly before the QCD phase transition critical temperature, depending on the ratio of the axion decay constants, $ \sim 1.69 $ . The cosmological evolution of the mass eigenvalues in these two scenarios is similar; however, the transition of axion energy density differs significantly. Finally, we estimate the relic density of the QCD axion dark matter in this context. Additionally, this level crossing may have some interesting cosmological implications.

Hai-Jun Li

Yu-Feng Zhou

Mass mixing between QCD axions * Supported by the CAS Project for Young Scientists in Basic Research YSBR-006, the National Key R&D Program of China (2017YFA0402204), and the National Natural Science Foundation of China (11821505, 11825506, 12047503)

Motivated by the gradual increase in experimental data, we revisit the couplings of axion-like particle (ALP) to electroweak gauge bosons across the ALP mass range from MeV to 100 GeV. We extend both current and projected experimental limits on these couplings, including the ALP couplings with $\textit{W}$-boson $ g_{aW} $ and hypercharge $\textit{B}$-boson $ g_{aB} $ . To clarify the contributions from electroweak boson couplings, we analyze and compare the resulting effects for various values of $ g_{aW} $ and $ g_{aB} $ . The couplings induce flavor-conserving ALP interactions with standard model fermions at the one-loop level, while $ g_{aW} $ additionally results in flavor-changing ALP-quark couplings. These phenomena warrant further investigation through rare meson decays and neutral meson mixing processes, particularly in light of recent results from $ B^+\to K^+\nu\bar{\nu} $ and $ K^+\to \pi^+\nu\bar{\nu} $ . We find that the rare two-body decays of pseudoscalar mesons offer the most sensitive probes below the kinematic threshold. In the high-mass region, complementary bounds arise from Pb-Pb collision and $\textit{Z}$-boson measurements, including the invisible decay $ Z\to a\gamma $ with subsequent ALP decays and constraints from oblique parameters ($\textit{S}$, $\textit{T}$, $\textit{U}$). Future lepton colliders, such as CEPC and FCC-ee operating at the $\textit{Z}$-pole, along with the search for hidden particles, provide further opportunities to probe ALP couplings to electroweak gauge bosons.

Jin Sun

Seokhoon Yun

Revisiting axion-like particle couplings to electroweak gauge bosons * Supported by IBS under the project code, (IBS-R018-D1) and NSFC (12375088, 12335003, 12405113)

The rigorous calculation of the spin-orbit terms in a three-quark system is realized based on the Gaussian expansion method and the infinitesimally-shifted Gaussian basis functions in the framework of the relativized quark model, by ignoring the mixing between different excited states. Then, the complete mass spectra of the singly heavy baryons are obtained rigorously, under the heavy-quark dominance mechanism. Accordingly, systematical analyses are performed for the reliability and predictive power of the model, the fine structure of the singly heavy baryon spectra, the assignments of the excited baryons, and some important topics about heavy baryon spectroscopy, such as the missing states, 'spin-orbit puzzle,' and clustering effect. The results confirm that, under the heavy-quark dominance mechanism, the relativized quark model can describe the excitation spectra and the fine structures of the singly heavy baryons correctly and precisely.

Zhen-Yu Li

Guo-Liang Yu

Zhi-Gang Wang

Jian-Zhong Gu

Hong-Tao Shen

Mass spectra of singly heavy baryons in the relativized quark model with heavy-quark dominance * Supported by the Open Project of Guangxi Key Lab of Nuclear Physics and Technology (NLK2023-04), the Central Government Guidance Funds for Local Scientific and Technological Development in China (Guike ZY22096024), the Natural Science Foundation of Guizhou Province-ZK[2024](General Project)650, the National Natural Science Foundation of China (11675265, 12175068), the Continuous Basic Scientific Research Project (WDJC-2019-13) and the Leading Innovation Project (LC 192209000701)

Recent anomalies observed in $ e^+e^- $ nuclear transitions of $ ^8 {{\rm{Be}}} $ , $ ^4 {\rm{He}} $ , and $ ^{12} {\rm{C}} $ by the ATOMKI collaboration may hint at the existence of a vector boson with a mass around 17 MeV, which is referred to as X17. If it exists, this boson would affect similar processes in particle physics, including the Dalitz decays of vector mesons. Recently, the BESIII collaboration measured the Dalitz decay $ D^{*0}\to D^0e^+e^- $ for the first time and reported a $ 3.5\sigma $ excess over the theoretical prediction based on the vector meson dominance (VMD) model. This excess may be another signal of X17. In this study, we investigate the possible effects of X17 on the Dalitz decays $ D^*_{(s)}\to D_{(s)}e^+e^- $ , $ B^*_{(s)}\to B_{(s)}e^+e^- $ , and $ J/\psi\to \eta_ce^+e^- $ . The required hadronic form factors are calculated within the framework of our covariant confined quark model without relying on heavy quark effective theory or the VMD model. We present predictions for the Dalitz decay widths and the ratios $ R_{ee}(V)\equiv \Gamma(V\to Pe^+e^-)/\Gamma(V\to P\gamma) $ within the standard model and in several new physics scenarios involving modifications attributed to X17. Our results are compared with other theoretical calculations.

Vietnam

C.T. Tran

Russia

M.A. Ivanov

A.T.T. Nguyen

Probing the ATOMKI X17 vector boson using Dalitz decays $\textit{V}$ → $\textit{Pe}$ $^{+}$ $\textit{e}$ $^{−}$ * Supported by Ho Chi Minh City University of Technology and Education (T2024-65)

Motivated by the first observation of $\rm CP $ violation in baryon decays, we study the topological amplitudes of bottom baryon decays in the $ S U(3)_{\rm F} $ limit. The topological diagrams of the charmless two-body decays of bottom baryons are presented in detail. The linear relations between topologies and $ S U(3) $ irreducible amplitudes are derived through tensor contraction and $ S U(3) $ decomposition. Four amplitudes among the 13 independent amplitudes are critical to the $\rm CP$ asymmetries. The small $ \rm CP $ asymmetries might indicate small relative strong phases between amplitudes $ A_2 $ and $ A_{12,14}^\prime $ . To avoid them, we suggest measuring $\rm CP $ asymmetries in the $ \Xi^0_b\to pK^- $ and $ \Xi^-_b\to \Lambda^0 K^- $ decays. Furthermore, the Körner-Pati-Woo theorem can be tested by measuring the branching fractions of the $ \Lambda_b^0\to\Sigma^0K^0_S $ and $ \Lambda_b^0\to\Sigma^-K^+ $ modes.

Di Wang

Wei-Chen Fu

Topological amplitudes of bottom baryon decays in the $\textit{SU}$(3)$_{F}$ limit * Supported in part by the National Natural Science Foundation of China (12105099)

We use a modified relativistic quark model to study the properties of excited charmed and charmed strange mesons. We calculate the masses and wave functions of conventional charmed and charmed strange mesons incorporating both spin and $\textit{S}$-$\textit{D}$ mixing effects and fit parameters of the potential model with known experimental states using differential evolution techniques. Using leading Born-Oppenheimer expansion, we compute the spectrum and wave functions of the first gluonic excited state of charmed and charmed strange mesons. We examine the effects of gluonic excitation on the spectrum of the resulting hybrid mesons. Using our calculated spectrum and wave functions, we determine the radiative transitions of the conventional and hybrid open charm mesons. We compare our calculations with experimental data and other works. We expect our results will be beneficial in the detection of charmed and charmed strange conventional and hybrid mesons.

Pakistan

Saba Noor

Faisal Akram

Bilal Masud

Study of excited $\textit{D}$ and D$_{s}$ mesons in a relativized quark model * F. A. acknowledges HEC grant 20-15728/NRPU/R&D/HEC/2021, Pakistan