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.

China

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

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 have implemented the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>3</mn><mo>+</mo><mn>1</mn></mrow></math> dimensional CLVisc hydrodynamics model with TrENTo-3D initial conditions to investigate the spin polarization of <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">Λ</mi></math> hyperons along the beam direction in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi mathvariant="normal">p</mi><mo>+</mo><mi>Pb</mi></mrow></math> collisions at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>8.16</mn></mrow></math> TeV. Following our previous theoretical framework based on quantum kinetic theory, we consider three different scenarios: <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">Λ</mi></math> equilibrium, <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>s</mi></math> quark equilibrium, and isothermal equilibrium scenarios. We have computed the second Fourier sine coefficients of spin polarization along the beam direction, denoted as <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>〈</mo><msub><mi>P</mi><mi>z</mi></msub><mo form="prefix">sin</mo><mn>2</mn><mrow><mo>(</mo><msub><mi>ϕ</mi><mi>p</mi></msub><mo>−</mo><msub><mi mathvariant="normal">Ψ</mi><mn>2</mn></msub><mo>)</mo></mrow><mo>〉</mo></mrow></math>, with <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>ϕ</mi><mi>p</mi></msub><mo>−</mo><msub><mi mathvariant="normal">Ψ</mi><mn>2</mn></msub></mrow></math> being the azimuthal angle relative to the second-order event plane <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi mathvariant="normal">Ψ</mi><mn>2</mn></msub></math>, as functions of multiplicity, transverse momentum, and pseudorapidity in the three scenarios. Additionally, we have also computed the spin polarization along the beam direction, <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>P</mi><mi>z</mi></msub></math>, as a function of the azimuthal angle. We find that the spin polarization induced by thermal vorticity always provides an opposite contribution compared to the shear-induced polarization in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi mathvariant="normal">p</mi><mo>+</mo><mi>Pb</mi></mrow></math> collisions. The total spin polarization computed by the current hydrodynamic model disagrees with the data measured by LHC-CMS experiments.

Cong Yi

United States

Canada

Xiang-Yu Wu

Germany

Jie Zhu

Shi Pu

Guang-You Qin

Spin polarization of <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">Λ</mi></math> hyperons along the beam direction in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mo>+</mo><mi>Pb</mi></mrow></math> collisions at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>8.16</mn></mrow></math> TeV using hydrodynamic approaches

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.

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.

We investigate the Klein-Gordon (KG) oscillators in a global monopole (GM) spacetime in Eddington-inspired Born-Infeld (EiBI) gravity and a Wu-Yang magnetic monopole (WYMM). We discuss the gravitational effects in the presence of Ricci scalar curvature <math altimg='si1.svg'><mi>R</mi><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><msubsup><mrow><mi>R</mi></mrow><mrow><mi>&#965;</mi></mrow><mrow><mi>&#965;</mi></mrow></msubsup></math>. It is observed that the presence of the Ricci scalar curvature, effectively and manifestly, introduces a force field that makes the corresponding quantum mechanical repulsive core more repulsive. Similar effect is also observed for the EiBI-gravitational field. We reiterate and report that the corresponding bosonic KG-oscillator quantum mechanical system admits a solution in the form of confluent Heun functions, the truncation of which into a physically admissible polynomial is shown to be associated with some parametric correlations/conditions. The use of such conditions/correlations is mandatory and yields a set of allowed/restricted quantum mechanical orbital <italic>&#8467;</italic>-excitations, for all radial quantum numbers <math altimg='si2.svg'><msub><mrow><mi>n</mi></mrow><mrow><mi>r</mi></mrow></msub><mo>&#8805;</mo><mn>0</mn></math>. Our procedure is shown to be quite handy, in the sense that it allows one to retrieve results for KG-oscillators in GM-spacetime in different EiBI-gravity and Ricci scalar curvature settings.

Türkiye

Omar Mustafa

KG-oscillators in Eddington-inspired Born-Infeld gravity: Wu-Yang magnetic monopole and Ricci scalar curvature effects

In the SMASH-CLVisc-hybrid framework, including SMASH for the initial conditions and the hadronic rescattering stage, and CLVisc for the quark gluon plasma evolution, we investigate net baryon number fluctuations via considering the equation of state (EoS) with and without a critical end point (CEP) in the quantum chromodynamic (QCD) phase transition. Specifically, two distinct QCD EoSs are utilized: one with smooth crossover derived from NEOS and another with a critical end point sourced from the rPNJL model. Our results show that nonmonotonic behavior of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>κ</mi><msup><mi>σ</mi><mn>2</mn></msup></mrow></math> is not observed above the collision energy <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>7.7</mn><mspace width="0.16em"></mspace><mi>GeV</mi></mrow></math>, nor are there explicit differences between the EoS characterized by crossover and that by CEP. This could be attributed to the significant deviation of the freeze-out line from the location of CEP. It is also found that the pure SMASH result of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>κ</mi><msup><mi>σ</mi><mn>2</mn></msup></mrow></math> is positive and close to zero at 3 GeV, which is different from the negative value observed from STAR.

Yifan Shen

Wei Chen

Kun Xu

Mei Huang

Net proton number cumulants from viscous hydrodynamics with an equation of state including a critical end point

Magnetic fields in heavy-ion collisions are pivotal and subject to diverse factors. In this study, we quantitatively investigate the impact of fluid vorticity on the evolution of magnetic fields in the 20%–50% centrality class in <math><mrow><mi>Au</mi><mo>+</mo><mi>Au</mi></mrow></math> collisions, with collision energies of <math><mrow><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt><mo>=</mo><mspace></mspace><mo>(</mo><mn>7.7</mn><mo>,</mo><mn>14.5</mn><mo>,</mo><mn>19.6</mn><mo>,</mo><mn>27</mn><mo>,</mo><mn>39</mn><mo>,</mo><mn>62.4</mn><mo>,</mo><mn>200</mn><mo>)</mo><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>. Our results indicate that fluid vorticity leads to a delay in the evolution of the magnetic field, in which this effect becomes more pronounced as the collision energy decreases. Additionally, we have calculated the mean magnetic field values on the freeze-out hypersurface for various collision energies. Our simulation results align with the values inferred from experimental data of <math><mover><mi>Λ</mi><mo>¯</mo></mover><mo>−</mo><mi>Λ</mi></math>, within the error margins.

Anping Huang

Effect of vorticity on the dynamical magnetic fields in heavy-ion collisions

We consider Klein–Gordon (KG) particles in a global monopole (GM) spacetime within Eddington-inspired Born–Infeld gravity (EiBI-gravity) and in a Wu–Yang magnetic monopole (WYMM). We discuss a set of KG-oscillators in such spacetime settings. We propose a textbook power series expansion for the KG radial wave function that allows us to retrieve the exact energy levels for KG-oscillators in a GM spacetime and a WYMM without EiBI-gravity. We, moreover, report some conditionally exact, closed form, energy levels (through some parametric correlations) for KG-oscillators in a GM spacetime and a WYMM within EiBI-gravity, and for massless KG-oscillators in a GM spacetime and a WYMM within EiBI-gravity under the influence of a Coulomb plus linear Lorentz scalar potential. We report the effects of the Eddington parameter $$\kappa $$ <math> <mi>κ</mi> </math> , GM-parameter $$\alpha $$ <math> <mi>α</mi> </math> , WYMM strength $$\sigma $$ <math> <mi>σ</mi> </math> , KG-oscillators’ frequency $$\Omega $$ <math> <mi>Ω</mi> </math> , and the coupling parameters of the Coulomb plus linear Lorentz scalar potential, on the spectroscopic structure of the KG-oscillators at hand. Such effects are studied over a vast range of the radial quantum number $$n_r\ge 0$$ <math> <mrow> <msub> <mi>n</mi> <mi>r</mi> </msub> <mo>≥</mo> <mn>0</mn> </mrow> </math> and include energy levels clustering at $$\kappa&gt;&gt;1$$ <math> <mrow> <mi>κ</mi> <mo>&gt;</mo> <mo>&gt;</mo> <mn>1</mn> </mrow> </math> (i.e., extreme EiBI-gravity), and at $$|\sigma |&gt;&gt;1$$ <math> <mrow> <mo>|</mo> <mi>σ</mi> <mo>|</mo> <mo>&gt;</mo> <mo>&gt;</mo> <mn>1</mn> </mrow> </math> (i.e., extreme WYMM strength).

Brazil

A. Soares

C. Pereira

R. Vitória

On the Klein–Gordon oscillators in Eddington-inspired Born-Infeld gravity global monopole spacetime and a Wu–Yang magnetic monopole