Building upon our previous work, this study extends the analysis to the rotating case and systematically examines the combined effects of magnetic charge, spin, and accretion flow structure on the resulting shadow and photon ring features. We derive the photon geodesics in the rotating Hayward spacetime via a semi-analytical approach and perform detailed ray-tracing simulations under both spherical and geometrically thin disk accretion scenarios. Our results demonstrate that the presence of magnetic charge induces significant deformations in the black hole (BH) shadow, most notably the emergence of a characteristic D-shaped asymmetry at high spin values and large inclination angles. Furthermore, we analyze the redshift and intensity distributions associated with both prograde and retrograde accretion disks, revealing that the observed image morphology is strongly influenced by relativistic Doppler boosting, gravitational redshift, and frame-dragging effects. Remarkably, the predicted brightness asymmetry and centroid displacement of the shadow images are in good agreement with current VLBI observations, such as those of M87 $$^{*}$$ . These findings underscore the potential of BH shadow imaging as a powerful probe of deviations from the classical Kerr geometry and offer theoretical guidance for interpreting future high-resolution observations.

China

Sen Guo

En-Wei Liang

Wen-Hao Deng

Qing-Quan Jiang

Yu Liang

Brazil

Kai Lin

Li-Fang Li

Modeling the shadow and ring structures of rotating Hayward black holes under magnetic charge and accretion influences

We investigate the discovery potential of the $T_{bc}$ state with $J^P = 0^+$ in proton-proton ( $pp$ ) collisions at LHCb at a center-of-mass energy of $\sqrt{s} = 13~{\rm{TeV}}$ . The study focuses on the decay channel $T_{bc} \to B^- D^+$ . A phenomenological approach is employed to construct the background model based on the associated production of $\textit{B}$ and $\textit{D}$ mesons, incorporating previously published LHCb results. Background processes are simulated using ${\mathtt{MadGraph5\_aMC@NLO}}$ and ${\mathtt{Pythia8.3}}$ . We explore the parameter space of the $T_{bc}$ mass, width, production cross section, and the effective double-parton scattering cross section ( $\sigma_{{\rm{eff}}}$ ) relevant for the $B D$ meson background. The integrated luminosity required for a $5\sigma$ discovery at LHCb is evaluated under various assumptions. In particular, we consider three representative $T_{bc}$ production cross section scenarios: an optimistic estimate of $103~{\rm{nb}}$ , an intermediate value of $18~{\rm{nb}}$ obtained by scaling from the $T_{cc}^+$ production cross section, and a conservative lower bound of $0.3~{\rm{nb}}$ . We find that a $5\sigma$ observation is achievable for a production cross section of $103~{\rm{nb}}$ , which is expected to be within reach during Run4. In contrast, the more realistic cross section estimate of $18~{\rm{nb}}$ requires the full Run5 dataset ( $300~{\rm{fb}}^{-1}$ ) under the most favorable parameter choices. For the conservative scenario, no significant signal would be observable even with $300~{\rm{fb}}^{-1}$ . In addition, we estimate the minimum observable $\sigma(T_{bc}) \times {\cal{B}}(T_{bc} \to $ $ B^- D^+)$ for a $5\sigma$ discovery under different luminosity scenarios, providing guidance for future experimental searches at LHCb.

Mingjie Feng

Yiming Li

France

Hua-Sheng Shao

Prospects for discovering strongly decaying doubly heavy T$_{bc}$ tetraquark states at LHCb * Mingjie Feng and Yiming Li is Supported by the National Natural Science Foundation of China (NSFC) (2175245, 12188102, W2443008). Hua-Sheng Shao is Supported by the European Research Council (101041109, 'BOSON') and the French National Research Agency (grant ANR-20-CE31-0015, 'PrecisOnium')

Using the ballistic approximation accretion flow model, this paper investigates the shadow and polarization images of a Kerr-like black hole surrounded by a cold dark matter halo. By numerically solving the geodesic and radiative transfer equations, we analyze the effects of the critical density $$r_c$$ , the scale radius of the dark matter halo $$r_s$$ , the spin parameter $\textit{a}$, and the observer inclination $$\theta _o$$ on the resulting images. In all cases, a bright ring structure corresponding to higher-order images is observed, accompanied by an inner region of decreased intensity. The results show that both $$r_c$$ and $$r_s$$ increase the size of the higher-order images, while the spin parameter $\textit{a}$ and inclination $$\theta _o$$ modify the image morphology, producing a crescent-shaped bright region on the left side. In the polarization maps, the linear polarization degree $$P_o$$ is significantly lower in the higher-order image region, and the polarization vectors exhibit distinct distributions inside and outside the ring. Compared with the thin disk model, the thick disk model displays notable differences in both shadow and polarization images.

Xiao-Xiong Zeng

Chen-Yu Yang

Ke-Jian He

The impact of cold dark matter halo on black hole shadow and polarization images under thick disk illumination

The Galactic Center GeV Excess (GCE) remains a compelling but enigmatic signal from the inner regions of our galaxy. Muonphilic dark matter (DM), which couples exclusively to muons via a new mediator, provides a viable explanation for the GCE and relic density while naturally evading constraints from direct detection, collider searches, and other multimessenger observations. Based on the viable nonresonant parameter space identified in previous global fits, we perform a comprehensive study on the prospects for discovering such muonphilic DM in the context of a future 3 TeV muon collider, focusing on simplified models with a $Z_2$ -even mediator. Four distinct search strategies are investigated: visible on-shell mediator decays ( $\mu^{+}\mu^{-}\gamma$ final state), invisible on-shell mediator decays (mono-photon plus missing energy), mono-photon production via off-shell mediators, and vector boson fusion production. Through a detailed signal-background analysis using cut-and-count methods, we project the exclusion limits at $ 95 $ % confidence level for seven representative models across a wide range of mediator masses. Our results demonstrate that the projected limits cover a significant portion of viable parameter space that explains the GCE, establishing a muon collider as a decisive machine for testing the muonphilic DM hypothesis.

Wanyun Chen

Haoqi Li

Chih-Ting Lu

Qiulei Wang

Exploring muonphilic dark matter with the $\textit{Z}$ $_{2}$-even mediator at muon colliders * Chih-Ting Lu, Wanyun Chen and Haoqi Li are supported by the National Natural Science Foundation of China (NNSFC) (12335005, 12575118) and the Special funds for postdoctoral overseas recruitment, Ministry of Education of China

This study investigates the ultraviolet realization of semileptonic four-fermion operator $ O_{ledq}^{\alpha \beta 11} $ that incorporates Majorana dark matter (DM) in both lepton-flavor-conserving (LFC) and lepton-flavor-violating (LFV) scenarios at the one-loop level via box diagram, thereby effectively alleviating the lower bounds on the new physics scale. In addition, we investigate the interplay between model-independent constraints on the Wilson coefficients and DM direct detection, relic density, and collider searches in the context of fermion portal DM model with two mediators. We found that both the projected future constraint on the LFC Wilson coefficient $ C_{ledq}^{2211}/\Lambda^2 \lt $ $ (12.3\; \text{TeV})^{-2} $ from the measurements of neutrino non-standard interaction in the next-generation neutrino oscillation experiments, and the LFV constraint $ C_{ledq}^{1211}/\Lambda^2 \lt \left(2.2\times 10^3\; \text{TeV} \right)^{-2} $ from ongoing charged-lepton-flavor-violation searches, provide a complementary exploration of the parameter space encompassing the DM and scalar masses. With a colored mediator mass of approximately $ 2\; \text{TeV} $ , the sensitivity of the indirect constraints on the four-fermion operator can surpass those of collider searches and DM direct detection, in scenarios where the masses of the DM and scalar are close. By ensuring the correct DM relic density, however, we find that the collider searches and DM direct detection are more sensitive to the electroweak-scale DM and scalar than indirect constraints.

Yuxuan He

Gang Li

Jia Liu

Xiao-Ping Wang

Xiang Zhao

Lepton flavor of four-fermion operator and fermion portal dark matter * Gang Li and Xiang Zhao are supported by the National Natural Science Foundation of China (12347105, 12505127), the Guangdong Basic and Applied Basic Research Foundation (2024A1515012668). The work of Jia Liu is supported by the National Science Foundation of China (12235001, 12475103) and State Key Laboratory of Nuclear Physics and Technology (NPT2025ZX11). The work of Xiao-Ping Wang is supported by National Science Foundation of China (12375095) and the Fundamental Research Funds for the Central Universities

This paper investigates the shadow images of rotating charged black holes in Kalb–Ramond (KR) gravity, using an accretion disk that is both optically and geometrically thin and located on the equatorial plane as the light source model. The results show that, compared to Sgr A*, the observational data of M87* impose stronger constraints on the charge parameter $\textit{Q}$ and the Lorentz-violating parameter $$\mathcal {G}$$ . Under the thin accretion disk model, a larger observer inclination $$\theta _o$$ deforms the central brightness depression into a hat-like structure. The parameters $$(a, Q, \mathcal {G})$$ mainly affect the size of the central brightness depression and the brightness of the critical curve, where increasing these parameters reduces the shadow size and enhances the distinguishability of the critical curve. In the retrograde accretion disk case, the crescent-shaped bright area appears on the side opposite to that in the prograde case. In addition, we compute the distribution of the redshift factor on the projection screen. The results indicate that the Doppler effect induced by large $$\theta _o$$ enhances the blueshift in the image, while the light emitted by particles plunging into the black hole leads to strong redshift near the central brightness depression. Finally, we study the polarization images under synchrotron radiation and find that the polarization intensity $$\mathcal {P}_o$$ reaches its maximum around the lensed image and higher-order images, whereas no polarization vectors appear within the central brightness depression. This stands in sharp contrast to horizonless compact objects. These findings contribute to a deeper understanding of the shadow properties of charged black holes within Lorentz-violating gravity.

Observational signatures and polarized images of rotating charged black holes in Kalb–Ramond gravity

Within the framework of Dyson-Schwinger equations (DSEs) and by means of the Multiple Reflection Expansion approximation, we study the finite volume effects on the constituent quark mass in a strong external magnetic field. Since the magnetic field influences the coupling constant, which controls the strength of strong interactions in QCD, we adopt the magnetic-field-dependent running coupling constant in our simulations. The results show that, in addition to the magnetic field, the masses of constituent quarks also have a significant dependence on the volume and the running coupling constant. The model behaves closely to the infinite volume limit for large sizes, but the effect of the finite volume is significant when the system size $\textit{R}$ is about $ 2-6 $ fm. The finite volume effects and the magnetic-field-dependent running coupling constant have considerable influence on the phase transition.

Li-Juan Zhou

De-Xian Wei

Zhong-Yi Liu

Hong-Wei Zhong

Dynamical quark mass and finite volume effects in the Dyson-Schwinger equations * Li-Juan Zhou has been supported by the National Natural Science Foundation of China (11865005), the Natural Science Foundation of Guangxi (China) (2025GXNSFAA069552). De-Xian Wei has been supported by the National Natural Science Foundation of China (12105057), the Natural Science Foundation of Guangxi (China) (2023GXNSFAA026020)

We report an experimental investigation of an unexplored breakup pathway of 6Li proceeding via one-proton stripping to the unbound 5He nucleus, followed by its decay into <math altimg='si22.svg'><mrow><mi>&#945;</mi><mo linebreak='goodbreak'>+</mo><mi>n</mi></mrow></math>, in the 6Li + 112Sn reaction at <math altimg='si3.svg'><mrow><msub><mi>E</mi><mrow><mrow><mi mathvariant='normal'>b</mi></mrow><mi>e</mi><mi>a</mi><mi>m</mi></mrow></msub><mo linebreak='goodbreak'>=</mo><mn>30</mn></mrow></math> MeV. Coincident <italic>&#945;</italic>- <italic>n</italic> events were measured using an array of silicon strip telescopes in conjunction with liquid scintillator neutron detectors. Successive kinematical cuts on the reconstructed projectile-like, fragment energies and Q-values enabled a clear separation of contributions arising purely through 5He <math altimg='si6.svg'><mrow><mo>&#8594;</mo><mi>&#945;</mi><mo linebreak='goodbreak'>+</mo><mi>n</mi></mrow></math> from competing processes such as evaporation following complete and incomplete fusion. The resultant relative energy distributions exhibit a pronounced peak at 0.84 MeV, indicating sequential breakup through the first unbound resonance 5He(3/2 <math altimg='si23.svg'><msup><mrow /><mo>&#8722;</mo></msup></math>) and show good agreement with Monte-Carlo simulations. Absolute breakup cross-sections for the ( 6Li, 5He&#8239;&#8594;&#8239; <italic>&#945;n</italic>) channel are determined using the efficiency-corrected yields. In addition, angular distributions for elastic scattering and breakup cross sections are interpreted within coupled-channels (CDCC+CRC) framework. The present results provide valuable insight into transfer-induced breakup dynamics of weakly bound nuclei near the Coulomb barrier.

India

Tanya Singh

S. Santra

P.C. Rout

A. Pal

A. Baishya

H. Kumawat

T. Santhosh

M. Meher

Jyotisankar Das

Ramandeep Gandhi

Sequential breakup of 6Li via ( 6Li, 5He <math altimg='si6.svg'><mrow><mo>&#8594;</mo><mi>&#945;</mi><mo linebreak='goodbreak'>+</mo><mi>n</mi></mrow></math>) reaction

A wide range of scintillating bolometers are under investigation for applications in the search for rare events and processes beyond the Standard Model. In this work, we report the first measurement of a natural, non-molybdenum-doped, lithium tungstate (Li $$_2$$ WO $$_4$$ ) crystal operated underground as a scintillating cryogenic calorimeter. The detector achieved a baseline energy resolution of 0.5 keV RMS with a low-energy threshold of about 1.5 keV. The simultaneous readout of heat and light enabled particle identification, revealing a clear separation between $$\beta /\gamma ,$$ $$\alpha ,$$ and nuclear recoil populations above 300 keV, with a light-yield-based particle discrimination better than $$6\sigma .$$ These results, fully comparable with those achieved with other compounds in the field, demonstrate that Li $$_2$$ WO $$_4$$ is a promising candidate for rare-event searches. In particular, the combination of excellent radio-purity (with U/Th levels below 0.5 mBq/kg) and sensitivity to neutron interactions via the $$^6$$ Li(n, $$\alpha )$$ $$^3$$ H reaction makes this material an attractive option for next-generation experiments in dark matter, coherent elastic neutrino-nucleus scattering, and spin-dependent interactions.

Italy

D. Helis

A. Melchiorre

S. Nagorny

Switzerland

M. Noia

L. Pagnanini

S. Pirro

A. Puiu

G. Benato

P. Carniti

R. Elleboro

P. Gambacorta

C. Gotti

Russia

V. Grigorieva

S. Nisi

E. Olivieri

G. Pessina

S. Piacentini

Kazakhstan

M. Shafiee

V. Shlegel

Characterization of the Li $$_2$$ WO $$_4$$ crystal as a cryogenic scintillating calorimeter

The competition between the breakup channels in the 6Li + 209Bi fusion reaction at the above-barrier energies has been investigated using a classical dynamic model. By incorporating the breakup processes from the short-lived nucleus formed via direct excitation and <italic>n</italic>-stripping, the model provides a comprehensive description of both complete and incomplete fusion cross sections. Although the <italic>n</italic>-stripping channel exhibits a higher probability, it contributes less to the complete fusion cross section compared to the direct excitation channel. An unexpected behavior was observed in incomplete fusion at the above barrier energies: the light-fragment capture predominantly occurs near the critical angular momentum, while the <italic>&#945;</italic> capture is favored at lower angular momenta, particularly in cases with large mass asymmetry between the two fragments. These findings provide further insight into the origin of fusion suppression in reactions involving weakly bound nuclei.

Kai-Xuan Cheng

Chun-Wang Ma

Mechanism of breakup channel competition in the 6Li+ 209Bi system at above-barrier energies