We investigate thermal photon production in the quark-gluon plasma (QGP) under strong magnetic fields using a magnetohydrodynamic (MHD) framework. We employ relativistic ideal fluid dynamics under the non-resistive approximation by adopting the Bjorken flow model with power-law decaying magnetic fields $ \mathbf{B}(\tau) = \mathbf{B}_0 (\tau_0/\tau)^a $ , span> $\textit{a}$ controls the decay rate, $ B_0 = \sqrt{\sigma} T_0^2 $ , and $\textit{σ}$ characterizes the initial field strength. The resulting QGP temperature evolution exhibits distinct $\textit{a}$- and $\textit{σ}$-dependent behaviors. Thermal photon production rates are calculated for three dominant processes: Compton scattering with $ q\bar{q} $ annihilation (C+A), bremsstrahlung (Brems), and $ q\bar{q} $ annihilation with additional scattering (A+S). These rates are integrated over the space-time volume to obtain the photon transverse momentum $ (p_T) $ spectrum. Our results demonstrate that increasing $\textit{a}$ enhances photon yields across all $ p_T $ , with $ a \to \infty $ (super-fast decay) providing an upper bound. For $ a = 2/3 $ , a larger $\textit{σ}$ suppresses yields through accelerated cooling, whereas for $ a \to \infty $ , a larger $\textit{σ}$ enhances yields via prolonged thermal emission. Low- $ p_T $ photons receive significant contributions from all QGP evolution stages, while high- $ p_T $ photons originate predominantly from early times. The central rapidity region $ (y=0) $ dominates the total yield. This work extends the photon yield studies to the MHD regime under strong magnetic fields, clarifying the magnetic field effects on QGP electromagnetic signatures and establishing foundations for future investigations of magnetization and dissipative phenomena.

China

Jie Xiong

Xiang Fan

Jing Jing

Weishan Yang

Duan She

Ze-Fang Jiang

Thermal photon emission from quark-gluon plasma: 1+1D magnetohydrodynamics results * Supported by the National Natural Science Foundation of China (NSFC) (12305138). Duan She's research is funded by the Startup Research Fund of Henan Academy of Sciences (231820058) and the 2024 Henan Province International Science and Technology Cooperation Projects (242102521068)

The charmed baryon was first observed experimentally in 1975, one year after the charm quark's confirmation via the discovery of the $ J/\psi $ particle. Studying charmed baryon decays provides a pathway to investigate both strong and weak interactions, leveraging the weak decays of the embedded charm quark. However, for approximately three decades following its discovery, experimental knowledge of charmed baryons remained significantly limited compared to those of the hidden-charm $\textit{ψ}$ mesons and open-charm $ D_{(s)} $ mesons. This situation changed markedly starting in 2014, when dedicated data collection for charmed baryons commenced at BESIII. In this article, we review the experimental progress achieved since 2014 in understanding the weak decays of the charmed baryons.

Pei-Rong Li

Xiao-Rui Lyu

Yangheng Zheng

Experimental overview on the charmed baryon decays * The authors thank Fusheng Yu for useful discussions. The authors are supported in part by National Natural Science Foundation of China (12221005, 12422504); CAS Project for Young Scientists in Basic Research (YSBR-117); Fundamental Research Funds for the Central Universities, Lanzhou University (lzujbky-2025-ytB01, lzujbky-2023-stlt01, lzujbky-2023-it32), University of Chinese Academy of Sciences

Electroweak (EW) amplitudes in the gauge-Goldstone five-component formalism have a distinctive property: gauge symmetry is imprinted in the amplitudes, manifested as the massive Ward identity (MWI) $ k^M{\cal{M}}_M=0 $ . In this study, we used the HELAS package to numerically study gauge symmetry in EW amplitudes. First, we directly tested gauge symmetry by examining the MWI of amplitudes. Second, we modified the couplings within a vertex and among vertices to check if and how the MWI changes. Third, we tested gauge symmetry by considering the couplings modified by operators from the standard model effective field theory (SMEFT). Similar to the standard model, there are relations between different couplings that are protected by gauge symmetry. We observed that, if we modify the couplings to deviate from the relations, the MWI is violated. In contrast, the MWI is restored when the relations between couplings reduce to those in the SMEFT.

Wang-Fa Li

Junmou Chen

Qian-Jiu Wang

Zhao-Huan Yu

Numerical study on the gauge symmetry of electroweak amplitudes * Junmou Chen is supported by National Natural Science Foundation of China (12205118), Wang-Fa Li, Qian-Jiu Wang, and Zhao-Huan Yu are supported by the Guangzhou Science and Technology Planning Project (2024A04J4026)

The high-density region of the QCD phase diagram displays an intricate competition between color superconductivity and the QCD Kondo effect due to color exchange in quark matter containing a single heavy quark impurity. We explore the characteristic impurity-induced superconducting subgap states arising in such systems by generalizing the surrogate model solver, recently considered in the context of condensed matter physics [<a href="http://dx.doi.org/10.1103/PhysRevB.108.L220506">Phys. Rev. B 108, L220506 (2023)</a>]. The method consists of approximating the full superconducting bulk by only a small number of effective levels whose parameters are chosen so as to best reproduce the Matsubara frequency dependence of the impurity-bulk hybridization function. We numerically solve a surrogate QCD Kondo model describing a quantum impurity color exchange coupled to a two-color two-flavor superconducting bulk. The results directly indicate the presence of multiple phase transitions as the coupling of the impurity to the bulk is increased, due to the interplay between various overscreened states. The methods introduced here are straightforward enough to be extended to more realistic QCD scenarios.

Romania

Virgil V. Baran

Denmark

Jens Paaske

Yu-Shiba-Rusinov states in color-superconducting quark matter

Motivated by the recent LHCb Collaboration analysis, we have investigated the process <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>−</mo></msup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>η</mi><mo>′</mo></msup><msup><mi>K</mi><mo>−</mo></msup></math> by considering the contributions from the resonances <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4710</mn><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>K</mi><mn>0</mn><mo>*</mo></msubsup><mo stretchy="false">(</mo><mn>1430</mn><mo stretchy="false">)</mo></math>. Our results are in good agreement with the measured invariant mass distributions and the Dalitz plot of LHCb, which supports the existence of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>K</mi><mn>0</mn><mo>*</mo></msubsup><mo stretchy="false">(</mo><mn>1430</mn><mo stretchy="false">)</mo></math> and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4710</mn><mo stretchy="false">)</mo></math> in the process <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>−</mo></msup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>η</mi><mo>′</mo></msup><msup><mi>K</mi><mo>−</mo></msup></math>. Since the decay mode of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4710</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>η</mi><mo>′</mo></msup></math> is Okubo-Zweig-Iizuka suppressed for the charmonium state, the measurements of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>Y</mi><mo stretchy="false">(</mo><mn>4710</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mrow><mi>η</mi></mrow><mrow><mo>′</mo></mrow></msup><mo stretchy="false">)</mo></mrow></math> through the process <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>−</mo></msup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>η</mi><mo>′</mo></msup><msup><mi>K</mi><mo>−</mo></msup></math> or other processes is helpful to understanding the nature of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4710</mn><mo stretchy="false">)</mo></math>. Thus, we advocate that Belle II and LHCb Collaborations could perform the more precise analysis to confirm the evidence of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4710</mn><mo stretchy="false">)</mo></math> state, which could be helpful to reduce the experimental uncertainties of its mass and width and to explore its nature.

Wen-Tao Lyu

Spain

Man-Yu Duan

De-Min Li

Bing Wang

Dian-Yong Chen

En Wang

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>−</mo></msup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>η</mi><mo>′</mo></msup><msup><mi>K</mi><mo>−</mo></msup></math> reaction and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4710</mn><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>K</mi><mn>0</mn><mo>*</mo></msubsup><mo stretchy="false">(</mo><mn>1430</mn><mo stretchy="false">)</mo></math> contributions

We study $ \cos2\phi $ azimuthal asymmetry in doubly longitudinally polarized proton-proton Drell-Yan collisions within the transverse momentum dependent factorization framework. The asymmetry arises from the convolution of the longitudinal transversity distribution $ h_{1L}^{\perp} $ for both protons. Using the Bacchetta-Delcarro-Pisano-Radici-Signori parameterization for the nonperturbative Sudakov form factor and the Wandzura-Wilczek approximation for collinear $ h_{1L}^{\perp} $ , we predict the double spin asymmetry $ A_{LL}^{\cos2\phi} $ at RHIC and NICA kinematics. Our results demonstrate sensitivity to sea quark distributions, with the asymmetry reaching up to 25% for maximal sea quark contributions. These predictions highlight the potential of polarized Drell-Yan measurements to probe sea quark dynamics and advance our understanding of nucleon structures.

Hui Li

Ting Hu

Liang-Liang Liu

Xiao-Yu Wang

Zhun Lu

Asymmetry ${{\boldsymbol A}_{\boldsymbol{LL}}^{\bf\cos2\boldsymbol\phi}} $ in the polarized proton-proton Drell-Yan process within TMD factorization * Hui Li is supported by Fundamental Research Program of Shanxi Province (202203021222224) and Natural Science Foundation of Shanxi Normal University (JCYJ2023021). Xiao-Yu Wang is supported by the Natural Science Foundation of Henan Province (242300421377, 232300421140)

We study the transverse momentum ( $p_T$ ) differential anisotropic flow and flow fluctuation in Pb+Pb collisions at $\sqrt{s_{_{NN}}}$ =5.02 TeV at the LHC. A (3+1)-dimensional CLVisc hydrodynamics framework with fluctuating TRENTO (or AMPT) initial conditions is utilized to simulate the space-time evolution of the quark-gluon plasma (QGP) medium. The effects of shear viscosity and the sub-nucleon structure on anisotropic flow and flow fluctuation are analyzed. Our result shows that shear viscosity tends to suppress both flow coefficients ( ${v_2\{2}\}$ , ${v_2\{4\}}$ , and ${\langle v_2\rangle}$ ) and flow fluctuation ( ${\sigma_{v_2}}$ ) owing to its smearing effect on local density fluctuation. The flow coefficients appear to be insensitive to the sub-nucleon structure, whereas the flow fluctuation ${\sigma_{v_2}}$ tends to be suppressed by the sub-nucleon structure in central collisions but enhanced in peripheral collisions. After taking into account the sub-nucleon structure effect, our numerical result can qualitatively describe the relative flow fluctuations ( ${v_2\{4\}/v_2\{2\}}$ , $F({v_2})$ ) measured by the ALICE Collaboration at the LHC. We further investigate the effects of shear viscosity, sub-nucleon structure, and initial condition model on the flow angle and flow magnitude decorrelations ( ${A_2^f}$ , ${M_2^f}$ ) using the four-particle correlation method. We find that the flow decorrelation effect is typically stronger in central collisions than in peripheral collisions. The flow angle decorrelation is found to be insensitive to the shear viscosity and sub-nucleon structure, whereas the flow magnitude decorrelation shows quite different behaviors when using the TRENTO and AMPT initial condition models. Our study sheds light on the anisotropic flow, transport properties, and initial structure of the QGP created in high-energy nuclear collisions.

Germany

Jie Zhu

Canada

Xiang-Yu Wu

Guang-You Qin

Anisotropic flow, flow fluctuation, and flow decorrelation in relativistic heavy-ion collisions: the roles of sub-nucleon structure and shear viscosity * Supported in part by the Natural Science Foundation of China (12225503, 11890710, 11890711, 11935007). Zhu Jie is supported in part by the China Scholarship Council (202306770009). Wu Xiang-Yu is supported in part by the National Science Foundation within the framework of the JETSCAPE collaboration (OAC-2004571) and in part by the Natural Sciences and Engineering Research Council of Canada. Some of the calculations were performed in the Nuclear Science Computing Center at Central China Normal University (NSC$^{3}$), Wuhan, Hubei, China.

Recently, the LHCb Collaboration has measured the processes $$B^+\rightarrow D^-D_s^+\pi ^+$$ and $$B^+\rightarrow \bar{D}^0D_s^+\pi ^+$$ , where the $$D_s^+\pi ^-$$ and $$D_s^+\pi ^+$$ invariant mass distributions show the significant signals of two new open-flavored tetraquark states $$T_{c\bar{s}}(2900)^0$$ and $$T_{c\bar{s}}(2900)^{++}$$ , as the two of the isospin triplet. In this work, we have investigated the process $$\Lambda _b\rightarrow K^0D^0\Lambda $$ by taking into account the tetraquark state $$T_{c\bar{s}}(2900)^0$$ and the intermediate nucleon resonance $$N^*(1535)$$ , which could be dynamically generated by the interactions of the $$D^*K^*/D^*_s\rho $$ and the pseudoscalar meson-octet baryon, respectively. Our results show that a clear peak of the open-flavored tetraquark $$T_{c\bar{s}}(2900)$$ may appear in the $$K^0D^0$$ invariant mass distribution of the process $$\Lambda _b\rightarrow K^0D^0\Lambda $$ , which could be tested by future experiments.

Yun-He Lyu

Guan-Ying Wang

Theoretical study of the open-flavored tetraquark $$T_{c\bar{s}}(2900)$$ in the process $$\Lambda _b\rightarrow K^0D^0\Lambda $$

Recently, the LHCb Collaboration has measured two decay processes $$B^0\rightarrow \bar{D}^0D_s^+\pi ^-$$ and $$B^+\rightarrow D^-D_s^+\pi ^+$$ related to isospin symmetry, where two new open-flavored tetraquark states $$T_{c\bar{s}}(2900)^0$$ and $$T_{c\bar{s}}(2900)^{++}$$ that belong to an isospin triplet were observed in the $$D_s^+\pi ^-$$ and $$D_s^+\pi ^+$$ invariant mass distributions. In this work, we have investigated the validity of the process $$\bar{B}_s^0\rightarrow K^0D^0\pi ^0$$ as the promising process to confirm the existence of $$T_{c\bar{s}}(2900)^0$$ resonance. Taking into account the tetraquark state $$T_{c\bar{s}}(2900)$$ , as well as intermediate resonances $$K^*(892)$$ , $$K_0^*(1430)$$ , and $$K_2^*(1430)$$ , it has been shown that a clear peak of the open-flavored tetraquark $$T_{c\bar{s}}(2900)$$ appears in the $$K^0D^0$$ invariant mass distribution of the process $$\bar{B}_s^0\rightarrow K^0D^0\pi ^0$$ , which could be tested by future experiments.

Xiaoyu Wang

Theoretical study of the open-flavored tetraquark $$T_{c\bar{s}}(2900)$$ in the process $$\bar{B}_s^0 \rightarrow K^0 D^0 \pi ^0$$

We study from the theoretical point of view the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><mi>η</mi><mi mathvariant="normal">Λ</mi></math> reaction, recently measured by the Belle and BESIII Collaborations, where clear signals are observed for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Λ</mi><mo stretchy="false">(</mo><mn>1670</mn><mo stretchy="false">)</mo></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Σ</mi><mo stretchy="false">(</mo><mn>1385</mn><mo stretchy="false">)</mo></math> excitation. By considering the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Λ</mi><mo stretchy="false">(</mo><mn>1670</mn><mo stretchy="false">)</mo></math> as dynamically generated resonances from the meson meson and meson baryon interaction, respectively, we are able to determine their relative production strengths in the reaction, which is also tied to the strength of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>π</mi><mo>+</mo></msup><mi>η</mi><mi mathvariant="normal">Λ</mi></math> tree level contribution. We observe that this latter strength is very big and there are large destructive interferences between the tree level and the rescattering terms where the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Λ</mi><mo stretchy="false">(</mo><mn>1670</mn><mo stretchy="false">)</mo></math> are generated. The <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Σ</mi><mo stretchy="false">(</mo><mn>1385</mn><mo stretchy="false">)</mo></math> contribution is included by means of a free parameter, the only one of the theory, up to a global normalization, when one considers only external emission, and we observe that the spin flip part of this term, usually ignored in theoretical and experimental works, plays an important role determining the shape of the mass distributions. Internal emission is also considered and it is found to play a minor role.

Chu-Wen Xiao

Ju-Jun Xie

Eulogio Oset

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi mathvariant="normal">Λ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo stretchy="false">→</mo><mi>η</mi><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><mi mathvariant="normal">Λ</mi></mrow></math> reaction and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">Λ</mi><msubsup><mrow><mi>a</mi></mrow><mrow><mn>0</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><mi mathvariant="normal">Λ</mi><mo stretchy="false">(</mo><mn>1670</mn><mo stretchy="false">)</mo></mrow></math> contributions