We present the first lattice result of the near threshold $ \Lambda_c\Lambda_c $ scattering with $ I(J^P) = 0(0^+) $ . The calculation is performed on two $ N_f = 2+1 $ Wilson-Clover ensembles with pion mass $ m_\pi \sim 303 $ MeV and lattice spacing $ a = 0.07746 $ fm. Lüscher's finite volume method is utilized to extract the scattering parameters from the finite-volume spectrum. The coupled channel $ \Xi_{cc}N $ is ignored in the scattering analysis based on the observation that the energy levels computed from the $ \Lambda_c\Lambda_c $ and $ \Xi_{cc}N $ operators do not mix. The $ \Sigma_c\Sigma_c $ channel is not included either since the energy range explored in this study is well below its threshold. Our results indicate that the interaction in the $ \Lambda_c\Lambda_c $ single channel is repulsive, and the scattering length is determined to be $ a_0 = -0.21(4)(8) $ fm, where the first error is statistical and the second is systematic.

China

Hanyang Xing

Yiqi Geng

Chuan Liu

Liuming Liu

Peng Sun

Jiajun Wu

Zhicheng Yan

Ruilin Zhu

Lattice QCD study of Λ $\textit{c}$ Λ $\textit{c}$ scattering * Supported by NSFC (12293060, 12293061, 12293063, 12175279, 12435002, 12322503, 12175239). L. Liu also acknowledges the Strategic Priority Research Program of the Chinese Academy of Sciences with (XDB34030301) and Guangdong Major Project of Basic and Applied Basic Research (2020B0301030008). We also acknowledge the Science and Education Integration Young Faculty Project of University of Chinese Academy of Sciences (YSBR-101)

<p>Within the framework of nonrelativistic quantum chromodynamics factorization, we calculate the next-to-leading order (NLO) perturbative QCD corrections to the form factors for the semileptonic decays of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>B</mi><mi>c</mi><mo>*</mo></msubsup></math> into <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> via (axial-)vector and (axial-)tensor currents. We obtain the complete analytical results for the form factors up to NLO, and provide their asymptotic expressions in the hierarchical heavy quark limit. The NLO corrections are found to be both significant and convergent in the relatively small squared transfer momentum (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>q</mi><mn>2</mn></msup></math>) region, while also reducing the dependence on the renormalization scale <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math>. Finally, the theoretical predictions for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>B</mi><mi>c</mi><mo>*</mo></msubsup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi></math> form factors over the full <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>q</mi><mn>2</mn></msup></math> range are provided.</p>

Qin Chang

Wei Tao

Zhen-Jun Xiao

Next-to-leading order QCD corrections to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>B</mi><mi>c</mi><mo>*</mo></msubsup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi></math> form factors

In this study, we investigate the $R^2$ corrections to the dissociation of heavy quarkonium in the Gauss-Bonnet gravitational background. We analyze the impact of the Gauss-Bonnet parameter $\lambda_{\rm GB}$ on the spectral function of charmonium and bottomonium and examine the effect of $\lambda_{\rm GB}$ on the dissociation of heavy quarkonium. Our results show that $\lambda_{\rm GB}$ reduces the peak height and increases the peak width of the spectral function, suggesting that $\lambda_{\rm GB}$ enhances the dissociation of heavy quarkonium. We also discuss the variation in the dissociation of heavy quarkonium with the ratio of shear viscosity to entropy density and observe that the dissociation is easier in more perfect plasma. Additionally, we observe that the temperature decreases the peak height and widens the peak, thereby accelerating the dissociation.

Zhou-Run Zhu

Manman Sun

Rui Zhou

Jinzhong Han

$\textit{R}$ $^{2}$ corrections to holographic heavy quarkonium dissociation * Rui Zhou supported by the Science and Technology Development Plan Project of Henan Province, China (242102230085), the National Natural Science Foundation of China (12404470), the High Level Talents Research and Startup Foundation Projects for Doctors of Zhoukou Normal University, China (ZKNUC2023017). Manman Sun supported by the National Natural Science Foundation of China (12305076). Zhou-Run Zhu supported by the High Level Talents Research and Startup Foundation Projects for Doctors of Zhoukou Normal University, China (ZKNUC2023018)

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.

The SU(3) analysis is considered a powerful tool in charmed baryon decays. Motivated by recent measurements of anti-triplet charmed baryon two-body decays from the Belle, Belle II, and BESIII Collaborations, we have finally determined the last two irreducible representation amplitude(IRA) form factors, $$f^{a\prime }$$ and $$g^{a\prime }$$ , which were absent in previous work. By considering both real and complex form factor cases in our work, we find that the phases of the form factors are necessary and that complex form factors can explain the experimental data well. Using the fitted form factors, we further numerically study the equivalence of the SU(3) IRA and topological diagrammatic approach (TDA) methods. We find that the IRA and TDA methods can be numerically equivalent with the addition of the new form factors. Based on the conclusions above, and considering some interesting scenarios, the CP violation(CPV) effects can be predicted in these processes at the order of $$O(10^{-3})$$ . This suggests a promising opportunity to observe CPV for the first time in charmed baryon decays. Although our predictions depend on some assumptions, considering that the experimental data is far from sufficient to determine CPV through SU(3) analysis, our study is meaningful and instructive for observing CPV at experimental facilities.

South Korea

Jin Sun

Zhi-Peng Xing

Analysis of charmed baryon decays with strong phases under SU(3) symmetry

We systematically examined the mass spectra and their two-body hadronic decays of the beauty-charm meson family considering coupled channel effects. Our results can effectively explain the observed   $B_c$   meson spectrum, and the prediction of the mass spectrum for unobserved beauty-charm mesons can be tested in future experiments. Compared with previous studies, we systematically examine the beauty-charm meson family within the coupled channel components. The   $B_c$   state in beauty-charm meson family has few percent of coupled channel component, while the   $B_c$  ,   $B_c$  , and   $B_c$   states have more than ten percent of coupled channel component. The two-body hadronic decay widths of the   $B_c$   state is as narrow as 3 MeV. The two-body hadronic decay widths of   $B_c$  ,   $B_c$  ,   $B_c$  ,   $B_c$  ,   $B_c$  , and   $B_c$   are approximately 109, 67, 60, 57, 201, and 76 MeV, respectively. Furthermore, the mixing effects between   $B_c$   and   $B_c$   states are discussed.

Wei Hao

Beauty-charm meson family with coupled channel effects and their strong decays  

Recently, the ATLAS and CMS collaborations jointly announced the first evidence of the rare Higgs boson decay channel <math><mi>H</mi><mo>→</mo><mi>Z</mi><mi>γ</mi></math>, with a ratio of <math><mn>2.2</mn><mo>±</mo><mn>0.7</mn></math> times the leading order standard model (SM) prediction. In order to face this challenge, it is urgent to produce an even more accurate calculation within the SM. To this end, we calculate in this paper the next-to-leading order (NLO) electroweak (EW) corrections to the <math><mi>H</mi><mo>→</mo><mi>Z</mi><mi>γ</mi></math> process, in which the NLO quantum chromodynamics (QCD) corrections were found tiny. Our calculation finds that the inclusion of NLO EW corrections greatly enhances the prediction reliability. To tame the theoretical uncertainty, we adopt five different renormalization schemes. Combining our result with previous NLO QCD corrections and the signal-background interference, we conclude that the excess in <math><mi>H</mi><mo>→</mo><mi>Z</mi><mi>γ</mi></math> cannot be explained within the SM. In fact, the incompatibility between the SM prediction and the LHC measurement of the concerned process is exacerbated upon considering the higher order EW corrections, which implies that something beyond the SM could be involved.

Zi-Qiang Chen

Long-Bin Chen

Cong-Feng Qiao

Two-loop electroweak corrections to the Higgs boson rare decay process <math><mi>H</mi><mo>→</mo><mi>Z</mi><mi>γ</mi></math>

Motivated by the very recent observation of the  $$B^+_c\rightarrow J/\psi +\pi ^+ +\pi ^0$$  <math> <mrow> <msubsup> <mi>B</mi> <mi>c</mi> <mo>+</mo> </msubsup> <mo>→</mo> <mi>J</mi> <mo>/</mo> <mi>ψ</mi> <mo>+</mo> <msup> <mi>π</mi> <mo>+</mo> </msup> <mo>+</mo> <msup> <mi>π</mi> <mn>0</mn> </msup> </mrow> </math>   decay using proton–proton collision data by the LHCb collaboration, we study the four-body angular distributions and the quantum entanglement effects in the  $$B^+_c\rightarrow J/\psi +\pi ^+ +\pi ^0$$  <math> <mrow> <msubsup> <mi>B</mi> <mi>c</mi> <mo>+</mo> </msubsup> <mo>→</mo> <mi>J</mi> <mo>/</mo> <mi>ψ</mi> <mo>+</mo> <msup> <mi>π</mi> <mo>+</mo> </msup> <mo>+</mo> <msup> <mi>π</mi> <mn>0</mn> </msup> </mrow> </math>   associated with  $$J/\psi \rightarrow \mu ^++\mu ^-.$$  <math> <mrow> <mi>J</mi> <mo>/</mo> <mi>ψ</mi> <mo>→</mo> <msup> <mi>μ</mi> <mo>+</mo> </msup> <mo>+</mo> <msup> <mi>μ</mi> <mo>-</mo> </msup> <mo>.</mo> </mrow> </math>   The helicity angular distributions are given in the QCD effective theory and the von Neumann entropy is obtained in  $$B^\pm _c\rightarrow J/\psi (\rightarrow \mu ^+\mu ^-)+\rho ^\pm (\rightarrow \pi ^\pm \pi ^0)$$  <math> <mrow> <msubsup> <mi>B</mi> <mi>c</mi> <mo>±</mo> </msubsup> <mo>→</mo> <mi>J</mi> <mo>/</mo> <mi>ψ</mi> <mrow> <mo>(</mo> <mo>→</mo> <msup> <mi>μ</mi> <mo>+</mo> </msup> <msup> <mi>μ</mi> <mo>-</mo> </msup> <mo>)</mo> </mrow> <mo>+</mo> <msup> <mi>ρ</mi> <mo>±</mo> </msup> <mrow> <mo>(</mo> <mo>→</mo> <msup> <mi>π</mi> <mo>±</mo> </msup> <msup> <mi>π</mi> <mn>0</mn> </msup> <mo>)</mo> </mrow> </mrow> </math>   decay process.

Kaiwen Chen

Yichao Jin

Polarization and quantum entanglement effects in  $$B^\pm _c\rightarrow J/\psi +\pi ^\pm +\pi ^0$$  <math> <mrow> <msubsup> <mi>B</mi> <mi>c</mi> <mo>±</mo> </msubsup> <mo>→</mo> <mi>J</mi> <mo>/</mo> <mi>ψ</mi> <mo>+</mo> <msup> <mi>π</mi> <mo>±</mo> </msup> <mo>+</mo> <msup> <mi>π</mi> <mn>0</mn> </msup> </mrow> </math>   process

To distinguish the low-lying vector beauty-charm meson, we systematically study the <math><msubsup><mi>B</mi><mi>c</mi><mo>*</mo></msubsup><mo>→</mo><msub><mi>B</mi><mi>c</mi></msub><mo>+</mo><mi>γ</mi></math>, <math><msubsup><mi>B</mi><mi>c</mi><mo>*</mo></msubsup><mo>→</mo><mo>ℓ</mo><mo>+</mo><msub><mi>ν</mi><mo>ℓ</mo></msub></math>, and <math><msubsup><mi>B</mi><mi>c</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msubsup><mo>→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>+</mo><mi>n</mi><mi>h</mi></math> processes within effective theory by the helicity decomposition method. The significant difference of polarization asymmetry in <math><msubsup><mi>B</mi><mi>c</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msubsup><mo>→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>+</mo><mi>n</mi><mi>h</mi></math> indicates a general law in vector-to-vector and pseudoscalar-to-vector transition processes, which can be tested in current and future LHC experiments. In the end, we discuss the experiment search and discovery potential for the low-lying vector beauty-charm meson.

Mingqi Cao

Distinguishing the low-lying vector beauty-charm meson via polarization analysis

Within the framework of non-relativistic QCD (NRQCD) factorization, we compute the matching coefficients between full Quantum Chromodynamics (QCD) and NRQCD for the heavy flavor-changing vector, axial-vector, scalar and pseudo-scalar currents up to next-to-next-to-next-to-leading order (N3LO). We accomplish the analytical expressions for the three-loop renormalization constants and the corresponding anomalous dimensions for all of the four NRQCD currents with two different heavy flavors. The three-loop QCD corrections to the matching coefficients turn out to be significantly larger than lower order corrections. By employing the scale relation, we approximately simulate the N3LO correction to the wave functions at the origin for the vector   <math> <msubsup> <mi>B</mi> <mi>c</mi> <mo>∗</mo> </msubsup> </math>  $$ {B}_c^{\ast } $$  meson and the pseudo-scalar B  c  meson from the known result for the equal-mass heavy quarkonium in potential NRQCD (pNRQCD). We find large cancellations at the third order between the matching coefficients and the wave functions at the origin, and obtain the convergent decay constants of   <math> <msubsup> <mi>B</mi> <mi>c</mi> <mo>∗</mo> </msubsup> </math>  $$ {B}_c^{\ast } $$  and B  c  up to N3LO. We present the complete perturbative QCD predictions for the decay constants, leptonic decay widths, and branching ratios of the beauty-charmed mesons.

Three-loop matching coefficients for heavy flavor-changing currents and the phenomenological applications