摘要
In 2021,the Belle collaboration reported the first observation of a new structure in theψ(2S)γfinal state produced in the two-photon fusion process.In the hadronic molecule picture,this new structure can be associatedwith the shallow isoscalar D*D* bound state and as such is an excellent candidate for the spin-2 partner of the X(3872)with the quantum numbers J^(PC)=2^(++)conventionally named X_(2).
基金
supported in part by the National Natural Science Foundation of China(Grant Nos.12070131001,12125507,11835015,and 12047503)
the Deutsche Forschungsgemeinschaft(DFG)through the funds provided to the Sino-German Collaborative Research Center TRR110“Symmetries and the Emergence of Structure in QCD”(Project-ID 196253076)
the Chinese Academy of Sciences(CAS)(Grant Nos.YSBR-101 and XDB34030000)
the EU STRONG-2020 project under the program H2020-INFRAIA-2018-1(Grant No.824093)
the Generalitat valenciana(GVA)for the project with ref.CIDEGENT/2019/015
supported by the Slovenian Research Agency(research core Funding No.P1-0035)
by CAS President’s International Fellowship Initiative(PIFI)(Grant No.2024PVA0004)。
