The Third Workshop on XYZ Particles was held at IHEP on April 1-3, 2015.The workshop was sponsored by IHEP scientists and was attended by 68 scholars from 17 universities and research institutions.

At the workshop, the latest experimental progress from BESIII and Belle experiments was discussed. Theoretical ideas on how to understand the data better from lattice QCD, QCD sum rules and effective theory were reviewed. The workshop brought together theoreticians and experimentalists to discuss what is necessary from the theoretical side to disentangle the different scenarios proposed as well as what is feasible experimentally in this respect in the foreseeable future.

In 2013, the BESIII collaboration announced the discovery of the exotic charged charmonium-like state Z_c(3900), that stimulated great interest in both experimental and theoretical research. With more data collected at BESIII, the spin-parity of the Z_c(3900) was determined to be 1+ in its DD* decays, the high mass partner Z_c(4020)/Z_c(4025) was observed, and the evidence for Y(4260) radiative transition into X(3872) was reported, together with the observation of a long searching D-wave charmonium state psi(3D2). BESIII has been accumulating more data for more studies and deeper understanding of the physics behind these observations, indicating very rich physics in this energy region. All the attendees of the workshop agree that an international workshop following the same line shall be organized in June at Shandong University to further discuss the topics.

This workshop was supported by the Ministry of Science and Technology, the National Natural Science Foundation of China and China Center for Advanced Science and Technology.

Workshop on XYZ Particles Held at IHEP （image by IHEP）