Overview of Bell and Bell II results

• 成平 沈

Overview of Bell and Bell II results

Heavy flavor spectroscopy study at LHCb

• 刘攀 安 (北京大学)

Studies on the spectroscopy of hadrons containing heavy quark(s) can deepen our understanding of the internal structure and dynamics of hadrons, thus improving our knowledge on the strong interaction, which is largely limited due to the non-perturbative behavior of Quantum Chromodynamics at low-energy regime. The discovery of a series of exotic heavy hadrons containing more than three valence quarks in the last decades has reinforced its importance. The LHCb experiment has been making significant contributions to such studies thanks to the large dataset provided by LHC and the delicate design of the detector. In this talk, a review of the heavy flavor spectroscopy study at LHCb will be presented.

Highlights of BESIII experiment

• 培荣 李

Highlights of BESIII experiment

格点QCD上的强子谱与强子结构

• Yi-Bo Yang (ITP/CAS)

我将介绍我们基于CLQCD组态上的夸克质量标定和强子能谱计算的进展，并概述近期国内在强子结构方面的格点QCD计算。

Status and prospect of electron ion collider in China

• Yutie Liang (Institute of Modern Physics, CAS)

核子（质子和中子的总称）大约占宇宙中可见物质总质量的99%。作为构成宇宙可见物质中的最主要成分,核子也是研究强相互作用, 尤其是禁闭区非微扰QCD的重要实验室。电子-离子对撞机(Electron Ion Collider, EIC)，被称作当代卢瑟福散射实验，是人类认识物质世界深层次结构，特别是核子结构的理想工具。中国极化电子离子对撞机项目设想在已开建的强流重离子加速器HIAF高能离子束的基础上升级建造中国电子-离子对撞机（EIC in China, EicC），为我国核物理与强子物理以及相关科学领域提供大型综合实验平台。在本报告中，我将主要介绍EicC重要物理亮点与探测器设计，并汇报项目进展。

四夸克态粒子在高能和B介子衰变中的产生

• 福升 于

The Progress of Super Tau-Charm Facility (STCF) in China

• 剑宇 张

FDC分波分析软件和BESIII重子激发态的研究

• Ronggang Ping (IHEP)

BESIII上已采集了大量的粲偶素衰变事例，包括100亿的J/psi和30亿的psi(3686). 它们衰变中产生大量的重子激发态，成为研究核子激发态和超子激发态的重要场所。报告将介绍费曼图自动计算（FDC）分波系统软件的GPU开发最新进展，和在重子激发态实验研究中的具体运用。

Cross-Channel Constraints on Resonant Antikaon-Nucleon Scattering

• 俊旭 陆

Cross-Channel Constraints on Resonant Antikaon-Nucleon Scattering

X(3872) Relevant D\bar{D}^* Scattering in $N_f=2$ Lattice QCD

• Chunjiang Shi (CAS, IHEP)

We study the S-wave D\bar{D}^*(I=0) scattering at four different pion masses m_\pi ranging from 250 MeV to 417 MeV from N_f=2 lattice QCD. A bound state near the D\bar{D}^* threshold likely exists even after considering the possible left-hand cut effect due to the one pion exchange interaction. At m_\pi\approx 417 MeV where the effective range expansion is valid, the compositeness of the bound state is X\approx 1 and indicates a predominant D\bar{D}^* component. This state may correspond to X(3872). On the other hand, our results of the finite volume energies also hint at the existence of a 1^{++} resonance below 4.0 GeV.

New insight into the exotic states strongly coupled with the $D\bar{D}^*$ from the $T^+_{cc}$

• GuangJuan Wang

New insight into the exotic states strongly coupled with the $D\bar{D}^*$ from the $T^+_{cc}$

Lattice calculation of Ds* radiative decay width

• Yu Meng (Zhengzhou University)

We perform a lattice calculation on the radiative decay of $D_s^*$ using the (2+1) Wilson-Clover gauge ensembles generated by CLQCD collaboration. The radiative transition $D_s^*\rightarrow D_s\gamma$ and Dalitz decay $D_s^*\rightarrow D_s e^+e^-$ are studied respectively. After a continuous extrapolation under three lattice spacings, we finally obtain these decay widths with much reduced errors compared to previous study. A poorly-known decay width of $D_s^*$ is also determined precisely taking into account the the experimental branching fraction.

Y(10753)的实验分析

• Junhao Yin (Nankai University)

Y(10753)的实验分析

Study of the tetraquark states

• 楮文 肖 (广西师范大学)

In the present work, we use the coupled channel formalism to investigate the mass spectrum of the tetraquark states. Starting from the local hidden gauge symmetry and considering the t- and u-channels, the two-body interaction potentials are evaluated, and then, the scattering amplitude is calculated with the coupled channel Bethe-Salpeter equation, where one can look for the resonance pole in the second Riemann sheet. In the heavy sector with strangeness, some results for the molecular states are shown.

Theoretical study of the low-lying excited baryons

• En Wang (Zhengzhou University)

Theoretical study of the low-lying excited baryons

Octet baryon and heavy meson interaction in chiral effective field theory

• 柏林 黄 (内蒙古大学)

Studies into baryon-meson interactions reveal significant insights into quantum chromodynamcis (QCD) at hadronic scales, forming a critical foundation for advancing hadron spectroscopy. We calculate the effective potentials of octet baryon and heavy meson systems using the chiral effective field theory up to the next-to-leading order. The low energy constants (LECs) are correlated with those of the \bar{N}N interaction using a quark-level Lagrangian approach. Our research provides new insights into several near-threshold charmed baryons [e.g., \Lambda_{c}(2940), \Xi_{c}(3055), and \Omega_{c}(3188), etc.] around 3 GeV from the hadronic molecular perspective. We also identify several molecular states, designated as \Xi_{c}, within the mass range of 3100-3500 MeV.

Revisiting O(N) σ model at unphysical pion masses and high temperatures

• 衢智 李 (Shanghai Jiao Tong University)

Roy-equation analyses on lattice data of ππ scattering phase shifts at mπ = 391MeV reveals that the lowest f0 meson becomes a bound state under this condition. In addition, there is a pair of complex poles below threshold generated by crossing symmetry [1]. We use the N/D method to partially recover crossing symmetry of the O(N ) σ model amplitude at leading order of 1/N expansion, and qualitatively reproduce the pole structure and pole trajectories with varying pion masses as revealed by Roy-equation analyses. The σ pole trajectory with varying temperature is also discussed and found to be similar to its properties when varying mπ . As the temperature increases, the complex σ poles firstly move from the second Riemann sheet to the real axis becoming two virtual state poles, and then one virtual state pole moves to the first sheet turning into a bound state pole and finally tends to the pion pole position at high temperature which is as expected from the chiral symmetry restoration. Our results provide further evidences that the lowest f0 state extracted from experiments and lattice data plays the role of σ meson in the spontaneous breaking of chiral symmetry. Finally, we also briefly discuss the problems of the effective potential in the situation when mπ and temperature get large.

具有隐藏定域对称性的夸克模型及其在强子谱学中的应用

• 秉然 何

We propose a chiral quark model that incorporates vector mesons and apply it to the study of the hadron spectrum. We consider the contributions of vector mesons within the framework of hidden local symmetry. Our results demonstrate a significant improvement in the masses of ground state baryons, including the nucleon, $\Lambda_c$, and $\Lambda_b$. We successfully reproduce the masses of all 45 experimentally confirmed ground states of mesons and baryons. Furthermore, our predictions for 21 ground states align well with the results obtained from lattice QCD analyses. This work represents the first successful achievement of all 45+21 ground states of mesons and baryons using a single set of parameters.

The relativistic three-body scattering and the D^0D^{*+}-D^+D^{*0} system

• Xu Zhang (Institute of Theoretical Physics, Chinese Academy of Sciences)

Scattering amplitudes involving three-particle scattering processes are investigated within the isobar approximation which respects constraints from two- and three-body unitarity. The particular system considered is the D^0D^{*+}-D^+D^{*0}, where the D^{*+}~(D^{*0}) enters as a p-wave D^+\pi^0 or D^0\pi^+~(D^0\pi^0 or D^+\pi^-) resonance. The interaction potentials in the coupled-channel D^0D^{*+}-D^+D^{*0} system contain the \sigma, \rho, \omega and \pi-exchange. The analytic continuation of the amplitudes across the three-body unitary cuts is investigated to search for poles on the unphysical Riemann sheets. Associated with an unstable particle D^{*+}~(D^{*0}) is a complex two-body unitarity cut, through which one can further analytically continue into another unphysical Riemann sheet. Dynamical singularities emerged from the $\pi$-exchange potential are stressed. The pole generated from the D^0D^{*+}-D^+D^{*0} interaction and its line shape in D^0D^0\pi^+ break-up production are in agreement with double-charmed tetraquark T_{cc}^+ observed by the LHCb Collaboration.

Light scalar mesons in semileptonic decay of charm meson at BESIII

• Shulei (书磊) Zhang (张) (Hunan University (湖南大学))

The nontrivial quark structure of light scalar mesons f0(500), f0(980) and a0(980) remains controversial for many years. In passed years, BESIII studied them via several semileptonic D decays (D0->a0(980)- e+nu, D+ -> a0(980)0 e+nu, Ds+ -> a0(980)0 e+nu, D+ -> f0(500)/f0(980)e+nu, D+ -> f0(500)mu+nu, Ds+ -> f0(500)/f0(980)e+nu). Especially, the measurement of D -> f0/a0 form factor could shed light on the nature of them. In this talk, I will review all studies about light scalar mesons via semileptonic D decays at BESIII. A short outlook would be given based on BESIII new data in the future.

Nucleon electroweak elastic and transition form factors

• 晨 陈

Nucleon properties are largely determined by the strong interaction; and a central aim of on-going experimental and theoretical efforts is to understand their structure as composite objects made of three valence light quarks. Electron+nucleon scattering is a well developed experimental technique in such studies and it has delivered, for instance, precise measurements of nucleon electromagnetic and transition form factors. An entirely new window onto nucleon and baryon structure is opened when one uses neutrino scattering. Indeed, reliable predictions of nucleon (N) and N-to-∆(1232) electroweak form factors are crucial for understanding new-generation long-baseline neutrino oscillation experiments. Recent developments within the framework of continuum Schwinger function methods (CSMs) have enabled practitioners to deliver the first Poincaré-invariant parameter-free predictions for such form factors. Where data are available, the predictions confirm the measurements. More importantly, the results are serving as motivation for new experiments at high-luminosity facilities. This presentation will describe nucleon electroweak elastic and transition form factors. Solving QCD is a hard problem and a many-pronged approach offers the best hope for success.

$\boldsymbol{P}$-wave states $\boldsymbol{T^-_{bb}}$ from diquarks

• 成荣 邓 (西南大学)

We investigate the $P$-wave states $T^-_{bb}$ in the isospin singlet and three excited modes [excitation occurring in the diquark $[bb]^{s_1}_{c_1}$ ($\rho $-mode), antidiquark $[\bar{u}\bar{d}]^{s_2}_{c_2}$ ($r$-mode) or between them ($\lambda$-mode)] from diquarks in a quark model. We analyze the dynamical behaviors of the diquark $[bb]^{s_1}_{c_1}$, antidiquark $[\bar{u}\bar{d}]^{s_2}_{c_2}$ and their correlations in the states $T^-_{bb}$ by decomposing the interactions from various sources in the model. The absolute dominant color-spin configuration, more than $99\%$, in the $\rho$-mode with $1^1P_1$ is $[bb]^0_{\bar{\mathbf{3}}}[\bar{u}\bar{d}]^0_{\mathbf{3}}$. Its energy is lower by about $18$ MeV than the threshold $\bar{B}\bar{B}$ so that it can establish a compact bound state. The chromomagnetic and meson-exchange interactions in the antidiquark $[\bar{u}\bar{d}]^0_{\mathbf{3}}$ are responsible for its binding mechanism. Two other excited modes are higher than their respective threshold. The color configuration $\mathbf{6}\otimes \bar{\mathbf{6}}$ need to be handled discreetly in the tetraquark states.

On the photoproduction of X(3872): insights from open-charm coupled-channel mechanism

• Xionghui Cao (Institute of Theoretical Physics)

Hidden-charm exotic hadrons such as X(3872) can be produced through the exclusive X(3872) photoproduction. The vector meson dominance model has been commonly employed in estimating the cross sections of such processes. However, the coupled-channel production mechanism through open-charm meson-baryon intermediate states may play a crucial role. To assess the significance of such contributions, we estimate the cross section assuming the coupled-channel mechanism. For energies near the threshold, the total cross section is predicted to be of tens of nanobarns, which can be measured at future experimental facilities. Furthermore, the open-charm coupled-channel mechanism leads to a distinct line shape of the total cross section that can be utilized to reveal the production dynamics.

Flavor-spin symmetry of the $P_c/H_c$ and $P_{cs}/H_{cs}$ molecular states

• kan chen (Northwest Unversity)

Based on a contact lagrangian possessing the SU(3) flavor and SU(2) spin symmetries, we discuss the symmetry properties of the interactions among the heavy flavor meson-baryon $P_c$ ([$n\bar{c}$][$nnc$]), $P_{cs}$ ([$s\bar{c}$][$nnc$] and [$n\bar{c}$][$nsc$]) systems and the baryon-baryon $H_c$ ([$nnc$][$ncc$]), $H_{cs}$ ([$nnc$][$scc$] and [$nsc$][$ncc$]) systems (with $n=u$, $d$). The light quark components of the $P_c$ ($P_{cs}$) and $H_{c}$ ($H_{cs}$) systems have identical flavors, the interactions generated from the exchanges of light mesons in the $P_c$ ($P_{cs}$) systems should be very similar to that of the $H_c$ ($H_{cs}$) systems. We perform the single-channel and multi-channel calculations on the $P_c/P_{cs}/H_c/H_{cs}$ systems and introduce the SU(3) breaking effect to identify the different mass spectra among the $P_c$ ($H_c$) and $P_{cs}$ ($H_{cs}$) systems. We suggest two kinds of evidences for the existence of the flavor-spin symmetry among the heavy flavor molecule community, i.e., the mass arrangement of the $P_c/H_c/P_{cs}/H_{cs}$ and the similar binding energies of the heavy flavor meson-baryon (baryon-baryon) systems with the same contact potentials.

Contact interaction study of proton parton distributions

• Yang Yu (Nanjing University)

Using a symmetry-preserving formulation of a vector × vector contact interaction (SCI) and treating the proton as a quark + interacting-diquark bound state, whose structure is obtained by solving a Poincare covariant Faddeev equation, we provide a comprehensive, coherent set of predictions for unpolarised and polarised proton parton distribution functions (DFs): valence, glue, and four-flavour separated sea. The results enable many themes to be addressed, including: the asymmetry of antimatter in the proton; the neutron:proton structure function ratio; helicity retention in hard scattering processes; the charm quark momentum fraction; the sign and size of the polarised gluon DF; and the origin of the proton spin. In all cases where sound analyses of data are available, SCI predictions are semiquantitatively in agreement with the results. Those mismatches which exist are typically attributable to the momentum-independence of the underlying interaction. Judiciously interpreted, the SCI delivers a sound and insightful explanation of proton structure as expressed in DFs.