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.

China

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.

In this work, we investigate the transition form factors for $$\Lambda _b\rightarrow {\Lambda (1520)}$$ within the framework of light-cone sum rules (LCSR), using the light-cone distribution amplitudes (LCDAs) of the $$\Lambda _b$$ -baryon. In the hadronic representation of the correlation function, we carefully select the appropriate Lorentz structures and isolate the contributions from both the $$\Lambda (1520)(J^P=(3/2)^-)$$ and the $$\Lambda (1890)(J^P=(3/2)^+),$$ ensuring that the form factors for $$\Lambda _b\rightarrow {\Lambda (1520)}$$ can be calculated unambiguously. We also provide predictions for various physical observables in the decay $$\Lambda _b\rightarrow {\Lambda (1520)}l^+l^-,$$ including the differential branching fraction, the lepton-side forward–backward asymmetry, the longitudinal polarization fraction, and the CP-averaged normalized angular observable. Our prediction for the differential branching fraction of $$\Lambda _b\rightarrow {\Lambda (1520)}\mu ^+\mu ^-$$ is in good agreement with the LHCb measurement within the uncertainties.

Ke-Sheng Huang

Hua-Yu Jiang

Fu-Sheng Yu

Transition form factors of the $$\Lambda _b \rightarrow \Lambda (1520)$$ in QCD light-cone sum rules

We present an improved calculation of the ( = ) , ) , = , , , and ) coupling constants beyond leading order in from QCD light-cone sum rules (LCSRs) by means of the light-cone distribution amplitudes (LCDAs) of light vector mesons. Near the light-cone, the next-to-leading order QCD corrections for the vacuum-to-vector-meson correlation function are included at leading power in = / ( = , ) within the framework of hard-collinear factorization. The higher-twist corrections from two-particle and three-particle vector meson LCDAs are systematically incorporated at leading order in by applying the method of background field in LCSRs. Based on these improvements, we perform a systematic computation of the strong coupling constants and extract the effective coupling of the heavy meson chiral perturbation theory (HM PT). Furthermore, we accomplish the analysis for the relation between the coupling and the residue of the → transition form factor at heavy pseudoscalar pole. Additionally, we provide a detailed investigation of the SU(3) flavour symmetry breaking effects and conduct a comparative analysis with results from previous studies.

Su-Ping Jin

Precision calculations of the

Making use of conformal symmetry of large- QCD in = 4 – 2 dimensions at the Wilson-Fischer fixed point, we calculate the two-loop coefficient functions in the operator product expansion of two electromagnetic currents in general kinematics with two different photon virtualities. This result is necessary for the description of the double deeply virtual Compton scattering to the next-to-next-to-leading order accuracy, but is also interesting for a range of other two-photon processes. We present analytic expression for the coefficient function in momentum fraction space in the $$ \overline{\textrm{MS}} $$ scheme and study its numerical impact on the Compton form factors for a simple model of the generalized parton distributions. The calculated corrections turn out to be large and are significant for the kinematics of proposed experiments.

Vladimir Braun

Alexander Manashov

Andreas Manteuffel

The two-loop coefficient functions for double deeply virtual Compton scattering

The dynamical studies on the non-leptonic weak decays of charmed baryons are always challenging, due to the large non-perturbative contributions at the charm scale. In this work, we develop the final-state rescattering mechanism to study the two-body non-leptonic decays of charmed baryons. The final-state interaction is a physical picture of long-distance effects. Instead of using the Cutkosky rule to calculate the hadronic triangle diagrams which can only provide the imaginary part of decay amplitudes, we point out that the loop integral is more appropriate, as both the real parts and the imaginary parts of amplitudes can be calculated completely. In this way, it can be obtained for the non-trivial strong phases which are essential to calculate CP violations. With the physical picture of long-distance effects and the reasonable method of calculations, it is amazingly achieved that all the nine existing experimental data of branching fractions for the   <math> <msubsup> <mi>Λ</mi> <mi>c</mi> <mo>+</mo> </msubsup> </math>  $$ {\Lambda}_c^{+} $$  decays into an octet light baryon and a vector meson can be explained by only one parameter of the model. Besides, the decay asymmetries and CP violations are not sensitive to the model parameter, since the dependence on the parameter is mainly cancelled in the ratios, so that the theoretical uncertainties on these observables are lowered down.

Cai-Ping Jia

Jian-Peng Wang

Final-state rescattering mechanism of charmed baryon decays

We present an improved calculation of the  $$D_{(s)}^*D_{(s)}V$$  <math> <mrow> <msubsup> <mi>D</mi> <mrow> <mo>(</mo> <mi>s</mi> <mo>)</mo> </mrow> <mo>∗</mo> </msubsup> <msub> <mi>D</mi> <mrow> <mo>(</mo> <mi>s</mi> <mo>)</mo> </mrow> </msub> <mi>V</mi> </mrow> </math>   and  $$B_{(s)}^*B_{(s)}V$$  <math> <mrow> <msubsup> <mi>B</mi> <mrow> <mo>(</mo> <mi>s</mi> <mo>)</mo> </mrow> <mo>∗</mo> </msubsup> <msub> <mi>B</mi> <mrow> <mo>(</mo> <mi>s</mi> <mo>)</mo> </mrow> </msub> <mi>V</mi> </mrow> </math>   coupling constants, where V denotes  $$\rho $$  <math> <mi>ρ</mi> </math>  ,  $$K^*$$  <math> <msup> <mi>K</mi> <mo>∗</mo> </msup> </math>  ,  $$\omega $$  <math> <mi>ω</mi> </math>  , and  $$\phi $$  <math> <mi>ϕ</mi> </math>   mesons. These couplings govern the long-distance quantum chromodynamics (QCD) in interactions between heavy pseudo-scalar/vector mesons and light vector mesons. Our analysis is conducted within the framework of QCD light-cone sum rules (LCSRs) by utilizing the light-cone distribution amplitudes (LCDAs) of light vector mesons. By systematically incorporating the subleading power corrections and higher-twist contributions at the leading order (LO) and including the next-to-leading order (NLO) corrections at leading power, we achieve enhanced accuracy in the light-cone operator product expansion (OPE) for the underlying correlation function. In assessing the reliability of the established LCSRs, we consider uncertainties arising from the choice of the quark–hadron duality region in the double dispersion relation. Building upon these improvements, we accomplish an optimized computation and analysis for the strong coupling constants  $$g_{H^*HV}$$  <math> <msub> <mi>g</mi> <mrow> <msup> <mi>H</mi> <mo>∗</mo> </msup> <mi>H</mi> <mi>V</mi> </mrow> </msub> </math>   which are used to extract the effective coupling  $$\lambda $$  <math> <mi>λ</mi> </math>   in the heavy meson chiral perturbation theory (HM $$\chi $$  <math> <mi>χ</mi> </math>  PT). Furthermore, we investigate the SU(3) flavor symmetry-breaking effects in detail and compare our sum rule calculations with previous studies in an exploratory way.

An improved calculation of the  $$D_{(s)}^*D_{(s)}V$$  <math> <mrow> <msubsup> <mi>D</mi> <mrow> <mo>(</mo> <mi>s</mi> <mo>)</mo> </mrow> <mo>∗</mo> </msubsup> <msub> <mi>D</mi> <mrow> <mo>(</mo> <mi>s</mi> <mo>)</mo> </mrow> </msub> <mi>V</mi> </mrow> </math>   and  $$B_{(s)}^*B_{(s)}V$$  <math> <mrow> <msubsup> <mi>B</mi> <mrow> <mo>(</mo> <mi>s</mi> <mo>)</mo> </mrow> <mo>∗</mo> </msubsup> <msub> <mi>B</mi> <mrow> <mo>(</mo> <mi>s</mi> <mo>)</mo> </mrow> </msub> <mi>V</mi> </mrow> </math>   couplings from light-cone sum rules

After the discovery of the double-charm baryon  $$\Xi _{cc}^{++}$$  <math> <msubsup> <mi>Ξ</mi> <mrow> <mi>cc</mi> </mrow> <mrow> <mo>+</mo> <mo>+</mo> </mrow> </msubsup> </math>   by LHCb, one of the most important topics is to search for the bottom-charm baryons which contain a b quark, a c quark and a light quark. In this work, we study the two-body non-leptonic weak decays of a bottom-charm baryon into a spin-1/2 bottomed baryon and a light pseudoscalar meson with the short-distance contributions calculated under the factorization hypothesis and the long-distance contributions considering the final-state-interaction effects. The branching fractions of all fifty-seven decay channels are estimated. The results indicate that  $$\Xi _{bc}^+\rightarrow \Xi _b^0\pi ^+$$  <math> <mrow> <msubsup> <mi>Ξ</mi> <mrow> <mi>bc</mi> </mrow> <mo>+</mo> </msubsup> <mo>→</mo> <msubsup> <mi>Ξ</mi> <mi>b</mi> <mn>0</mn> </msubsup> <msup> <mi>π</mi> <mo>+</mo> </msup> </mrow> </math>  ,  $$\Xi _{bc}^{0}\rightarrow \Xi _{b}^{-}\pi ^+$$  <math> <mrow> <msubsup> <mi>Ξ</mi> <mrow> <mi>bc</mi> </mrow> <mn>0</mn> </msubsup> <mo>→</mo> <msubsup> <mi>Ξ</mi> <mrow> <mi>b</mi> </mrow> <mo>-</mo> </msubsup> <msup> <mi>π</mi> <mo>+</mo> </msup> </mrow> </math>   and  $$\Omega _{bc}^0\rightarrow \Omega _b^-\pi ^+$$  <math> <mrow> <msubsup> <mi>Ω</mi> <mrow> <mi>bc</mi> </mrow> <mn>0</mn> </msubsup> <mo>→</mo> <msubsup> <mi>Ω</mi> <mi>b</mi> <mo>-</mo> </msubsup> <msup> <mi>π</mi> <mo>+</mo> </msup> </mrow> </math>   decay modes have relatively large decay rates and thus could be used to experimentally search for the bottom-charm baryons. The topological diagrams and the SU(3) symmetry of bottom-charm baryon decays are discussed.

Jia-Jie Han

Rui-Xiang Zhang

Zhen-Jun Xiao

Weak decays of bottom-charm baryons:  $$\mathcal {B}_{bc}\rightarrow \mathcal {B}_bP$$  <math> <mrow> <msub> <mi>B</mi> <mrow> <mi>bc</mi> </mrow> </msub> <mo>→</mo> <msub> <mi>B</mi> <mi>b</mi> </msub> <mi>P</mi> </mrow> </math>

The doubly charmed baryon   $ \Xi_{cc}^{++} $   was recently observed by LHCb via the decay processes of   $ \Xi_{cc}^{++} $   and   $ \Xi_{cc}^{++} $  . These discovery channels were successfully predicted in a framework in which the short-distance contributions are calculated under the factorization hypothesis and the long-distance contributions are estimated using the rescattering mechanism for the final-state-interaction effects. In this paper, we illustrate the above framework in detail by systematic studies on the two-body baryonic decays   $ \Xi_{cc}^{++} $   involving the doubly charmed baryons   $ \Xi_{cc}^{++} $  , the singly charmed baryons   $ \Xi_{cc}^{++} $   and the light pseudoscalar mesons   $ \Xi_{cc}^{++} $  .

Wei Liu

Rescattering mechanism of weak decays of double-charm baryons  

Using the vector exchange interaction in the local hidden gauge approach, which in the light quark sector generates the chiral Lagrangians and has produced realistic results for 
					 and the hidden charm pentaquark states, we study the meson-baryon interactions in the coupled channels that lead to the 
					 and 
					 excited states of the molecular type. We obtain seven states of the 
					 type with energies between 
					 and 
					 MeV, and one 
					 state at 
					 MeV.
				

Brazil

J. M. Dias

Qi-Xin Yu

Wei-Hong Liang

Zhi-Feng Sun

Ju-Jun Xie

Spain

E. Oset

Ξbb and Ωbbb molecular states Partly supported by the National Natural Science Foundation of China (11975083, 11947413, 11847317, 11565007, 11735003, 1191101015). Q. X Yu acknowledges the support from the National Natural Science Foundation of China (11775024, 11575023, 11805153) and China Scholarship Council. Partly supported by the Spanish Ministerio de Economia y Competitividad and European FEDER funds (FIS2017- 84038-C2-1-P B, FIS2017-84038-C2-2-P B), and the Generalitat Valenciana in the program Prometeo II-2014/068, and the project Severo Ochoa of IFIC, SEV-2014-0398

We calculate the mixing parameter y in the factorization-assisted topological-amplitude (FAT) approach, considering contributions from , PV, and VV modes, where P (V) stands for a pseudoscalar (vector) meson. The and PV decay amplitudes are extracted in the FAT approach, and the decay amplitudes with final states in the longitudinal polarization are estimated via the parameter set for . It is found that the VV contribution to y, being of order of 10−4, is negligible, and that the PP and PV contributions amount only up to , a prediction more precise than those previously obtained in the literature, and much lower than the experimental data . We conclude that D0 meson decays into other two-body and multi-particle final states are relevant to the evaluation of y, so it is difficult to understand it fully in an exclusive approach.

Qin Qin

Taiwan

Hsiang-nan Li

Cai-Dian Lü

D0-D̄0 mixing parameter y in the factorization-assisted topological-amplitude approachSupported by National Natural Science Foundation of China (11347027, 11505083, 11375208, 11521505, 1162113100, 11235005, U1732101), Ministry of Science and Technology of R.O.C. (MOST-104-2112-M-001-037-MY3) and DFG Forschergruppe FOR 1873 “Quark Flavour Physics and Effective Field Theories”