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。
We have investigated the electromagnetic form factors of charmed $\Lambda_c^+$ baryon and the total cross sections of the $𝑒^+𝑒^− \to 𝛬^+_c \bar{\Lambda}_c^-$ reaction within the extended vector meson dominance model. By including the charmonium-like states 𝜓(4500), 𝜓(4660), 𝜓(4790), and the possible 𝜓(4900) state, the current experimental data can be well reproduced.
In a previous paper, it was pointed out that the wave functions of all particles are not pure waves, besides the main partial waves, they all contain other partial waves. It is very interesting to know what role these different partial waves play in particle transitions. Therefore, by using the Bethe-Salpeter equation method, we study the radiative electromagnetic decays...
Exclusive photoproduction of heavy vector mesons from the proton is widely assumed to proceed via mechanisms that are sensitive to glue physics in the target proton. It was once thought that vector meson dominance could be used to relate this photoproduction process to the in-proton expectation value of the trace anomaly in quantum chromodynamics (QCD); hence, to deliver insights into the...
In this presentation, I will show our recent results on calculating the gluon-exchange contribution to the $J/\Psi N$ scattering length via dispersion relations. Additionally, I will compare these results with others to facilitate further discussion.
Exploiting crossing symmetry, the pion valence quark distribution function (DF) is used to predict the pion fragmentation function (FF). In this way, a unified treatment of the pion DFs and FFs was accomplished. The significance of this work lies in that it is the first prediction of FFs in any approach with a traceable connection to quantum chromodynamics (QCD), and it also gives insights...
We study the latest non-trivial resonant line-shape of $\eta(1405 /1475)$ in the $K \bar{K}\pi$ invariant mass spectrum measured by the BESIII. The possible existence of two isoscalar pseudoscalars around 1.4 ~1.5 GeV is in contradiction with the nonet structure in the SU(3) flavor symmetry. Nevertheless, the glueball assignment of the outnumbering state is not favored by the Lattice QCD...
In this work, we investigated in detail the widths of the $X_2$ decaying to $J/ \psi V$ ($V = \rho^0\,,\omega$) and to $\eta_cP$ ($P = \pi^0\,,\eta\,,\eta'$) using the effective Lagrangian approach. In calculations, we assume the $X_2$ as a molecular state of the $D^{*0}\bar{D}^{*0} $ and $D^{*+}D^{*-}$ with equal proportion. Moreover, we only consider the contributions from the triangle...
The BESIII Collaboration recently observed a new charmonium-like vector state Y(3872) in e^+e^-\rightarrow D\bar{D}^, which should be the first P-wave D\bar{D}^ molecular resonance. The experimental and theoretical identification of the P-wave dimeson state holds paramount importance in enhancing our comprehension of the non-perturbative QCD and few-body physics. Its existence is firmly...
In this talk, I will present our recent study on the low lying axial-vector meson spectrum, which is an extention of our study on eta1(1855).
We study three-body systems \eta K^ \bar{K}^, \pi K^ \bar{K}^ and K K^ \bar{K}^ by Faddeev fixed-center approximation. Under fixed-center approximation framework, we can view a three-body system as a cluster which is generated by two particles in system and the third particle, where we view K^ \bar{K}^cluster as f_0(1710), a_0(1710) and f_2’(1525), respectively, and scatter \eta, \pi...
We propose an unquenched quark model for describing the heavy-light mesons by taking into account the coupled-channel effects induced by chiral dynamics. After including a relativistic correction term for the strong transition amplitudes, both the mass spectra and decay widths of the observed heavy-light mesons can be successfully described simultaneously in a unified framework, several...
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。
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...
New insight into the exotic states strongly coupled with the
$D\bar{D}^*$ from the $T^+_{cc}$
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...
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...
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...
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...
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,...
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...
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...
